# The &kmplot; Handbook

Klaus-Dieter
Möller

    &Klaus-Dieter.Moeller.mail;

&Philip.Rodrigues; &Philip.Rodrigues.mail;
David
Saxton
2000
2001
2002
Klaus-Dieter Möller
2003
&Philip.Rodrigues; &Philip.Rodrigues.mail;
2006
David Saxton
&FDLNotice;
2019-01-16
1.3.0 (Applications 19.04)

&kmplot; is a mathematical function plotter by &kde;.

&kmplot; is part of the &kde;-EDU Project: https://edu.kde.org/

KDE
KmPlot
EDU
education
plotting
math

## Introduction

&kmplot; is a mathematical function plotter by &kde;. It has a powerful built-in parser. You can plot different functions simultaneously and combine them to build new functions.

Examples
Examples

&kmplot; supports several different types of plots:

- Explicit cartesian plots of the form y = f(x).

- Parametric plots, where the x and y components are specified as functions of an independent variable.

- Polar plots of the form r = r(&thgr;).

- Implicit plots, where the x and y coordinates are related by an expression.

- Explicit differential plots.

&kmplot; also provides some numerical and visual features like:

- Filling and calculating the area between the plot and the first axis

- Finding maximum and minimum values

- Changing function parameters dynamically

- Plotting derivatives and integral functions.

These features help in learning the relationship between mathematical functions and their graphical representation in a coordinate system.

## First Steps With &kmplot;

### Simple Function Plot

In the sidebar on the left, there is the Create button with a drop down menu for creating new plots. Click on it, and select Cartesian Plot. The text box for editing the current equation will be focused. Replace the default text with

    y = x^2

and press &Enter;. This will draw the plot of y = x2 in the coordinate system. Clicking on the Create button again, select Cartesian Plot, and this time enter the text

    y = 5sin(x)

to get another plot.

Drag and drop the item `y = 5sin(x)` in the left sidebar to clone the plot. Replace `sin` with `cos` to get the cosine plot of the same color.

Click on one of the lines you have just plotted. Now the crosshair becomes the color of the current plot and is attached to the it. You can use the mouse to move the crosshair along the plot. In the status bar at the bottom of the window the coordinates of the current position is displayed. Note that if the plot touches the horizontal axis the root will be displayed in the status bar, too.

Click the mouse again and the crosshair will be detached from the plot.

### Edit Properties

Let us make some changes to the function and change the color of the plot.

The Functions sidebar lists all the functions that you have plotted. If y = x^2 isn't already selected, select it. Here you have access to a lot of options. Let us rename the function and move the plot 5 units down. Change the function equation to

    parabola(x) = x^2 - 5

and hit enter. To select another color for the plot, click the Color button in the section Appearance at the bottom of the function sidebar and select a new color.

All changes can be undone via Edit Undo .

## Using &kmplot;

&kmplot; deals with several different types of functions, which can be written in function form or as an equation:

- Cartesian plots can either be written as &eg; y = x^2, where x has to be used as the variable; or as &eg; f(a) = a^2, where the name of the variable is arbitrary.

- Parametric plots are similar to Cartesian plots. The x and y coordinates can be entered as equations in t, &eg; x = sin(t), y = cos(t), or as functions, &eg; f_x(s) = sin(s), f_y(s) = cos(s).

- Polar plots are also similar to Cartesian plots. They can be either be entered as an equation in &thgr;, &eg; r = &thgr;, or as a function, &eg; f(x) = x.

- For implicit plots, the name of the function is entered separately from the expression relating the x and y coordinates. If the x and y variables are specified via the function name (by entering &eg;f(a,b) as the function name), then these variables will be used. Otherwise, the letters x and y will be used for the variables.

- Explicit differential plots are differential equations whereby the highest derivative is given in terms of the lower derivatives. Differentiation is denoted by a prime ('). In function form, the equation will look like f''(x) = f' − f. In equation form, it will look like y'' = y' − y. Note that in both cases, the (x) part is not added to the lower order differential terms (so you would enter f'(x) = −f and not f'(x) = −f(x)).

All the equation entry boxes come with a button on the right. Clicking this invokes the advanced Equation Editor dialog, which provides:

- A variety of mathematical symbols that can be used in equations, but aren't found on normal keyboards.

- The list of user constants and a button for editing them.

- The list of predefined functions. Note that if you have text already selected, it will be used as the function argument when a function is inserted. For example, if 1 + x is selected in the equation y = 1 + x, and the sine function is chosen, then the equation will become y = sin(1+x).

Here is a screenshot of the &kmplot; welcome window
Screenshot

### Function Types

#### Cartesian Functions

To enter an explicit function (&ie;, a function in the form y=f(x)) into &kmplot;, just enter it in the following form:

    f(x) = expression

where:

- f is the name of the function, and can be any string of letters and numbers.

- x is the horizontal coordinate, to be used in the expression following the equals sign. It is a dummy variable, so you can use any variable name you like to achieve the same effect.

- expression is the expression to be plotted, given in the appropriate syntax for &kmplot;. See .

#### Parametric Functions

Parametric functions are those in which the x and y coordinates are defined by separate functions of another variable, often called t. To enter a parametric function in &kmplot;, follow the procedure as for a Cartesian function for each of the x and y functions. As with Cartesian functions, you may use any variable name you wish for the parameter.

As an example, suppose you want to draw a circle, which has parametric equations x = sin(t), y = cos(t). After creating a parametric plot, enter the appropriate equations in the x and y boxes, &ie;, `f_x(t)=sin(t)` and `f_y(t)=cos(t)`.

You can set some further options for the plot in the function editor:

Min
Max

  These options control the range of the parameter t for which the function is plotted.

#### Functions in Polar Coordinates

Polar coordinates represent a point by its distance from the origin (usually called r), and the angle a line from the origin to the point makes with the horizontal axis (usually represented by &thgr; the Greek letter theta). To enter functions in polar coordinates, click the Create button and select Polar Plot from the list. In the definition box, complete the function definition, including the name of the theta variable you want to use, &eg;, to draw the Archimedes' spiral r = &thgr;, enter:

    r(&thgr;) = &thgr;

Note that you can use any name for the theta variable, so r(t) = t or f(x) = x will produce exactly the same output.

#### Implicit Functions

An implicit expression relates the x and y coordinates as an equality. To create a circle, for example, click the Create button and select Implicit Plot from the list. Then, enter into the equation box (below the function name box) the following:

    x^2 + y^2 = 25

#### Differential Functions

&kmplot; can plot explicit differential equations. These are equations of the form y(n) = F(x,y',y'',...,y(n−1)), where yk is the kth derivative of y(x). &kmplot; can only interpret the derivative order as the number of primes following the function name.

To draw a sinusoidal curve, for example, you would use the differential equation `y'' = − y` or `f''(x) = −f`.

However, a differential equation on its own isn't enough to determine a plot. Each curve in the diagram is generated by a combination of the differential equation and the initial conditions. You can edit the initial conditions by clicking on the Initial Conditions tab when a differential equation is selected. The number of columns provided for editing the initial conditions is dependent on the order of the differential equation.

You can set some further options for the plot in the function editor:

Step

  The step value in the precision box is used in numerically solving the differential equation (using the Runge Kutta method). Its value is the maximum step size used; a smaller step size may be used if part of the differential plot is zoomed in close enough.

### Combining Functions

Functions can be combined to produce new ones. Simply enter the functions after the equals sign in an expression as if the functions were variables. For example, if you have defined functions f(x) and g(x), you can plot the sum of f and g with:

    sum(x) = f(x) + g(x)

### Changing the appearance of functions

To change the appearance of a function's graph on the main plot window, select the function in the Functions sidebar. You can change the plot's line width, color and many other aspects by clicking on the Color or Advanced... button at the bottom of the section Appearance.

If you are editing a Cartesian function, the function editor will have three tabs. In the first one you specify the equation of the function. The Derivatives tab lets you draw the first and second derivative to the function. With the Integral tab you can draw the integral of the function.

### Popup menu

Graph right-click popup menu
Graph right-click popup menu

When right-clicking on a plot function or a single-point parametric plot function a popup menu will appear. In the menu there are five items available:

Edit

  Selects the function in the Functions sidebar for editing.

Hide

  Hides the selected graph. Other plots of the graph's function will still be shown.

Remove

  Removes the function. All its graphs will disappear.

Animate Plot...

  Displays the Parameter Animator dialog.

Calculator

  Opens the Calculator dialog.

Depending on the plot type, there will also be up to five tools available:

Copy (x, y)

  Copies the current value on the plot to the system clipboard. This tool can be useful for creating tables of function values outside of &kmplot;.

Copy Root Value

  Copies the root `x` value to the system clipboard. Only up to the first five digits after the decimal point can be copied. Use some computer algebra system to determine this root with arbitrary precision. This tool is only available when the current tracking position is close to a root.

Plot Area...

  Select the minimum and maximum horizontal values for the graph in the new dialog that appears. Calculates the integral and draws the area between the graph and the horizontal axis in the selected range in the color of the graph.

Find Minimum...

  Find the minimum value of the graph in a specified range. The selected graph will be highlighted in the dialog that appears. Enter the lower and upper boundaries of the region in which you want to search for a minimum.

  Note: You can also tell the plot to visually show the extreme points in the Plot Appearance dialog, accessible in the Functions sidebar by clicking on Advanced....

Find Maximum...

  This is the same as Find Minimum... above, but finds the maximum value instead of the minimum value.

## Configuring &kmplot;

To access the &kmplot; configuration dialog, select Settings Configure &kmplot;... The settings for Constants... can only be changed from the Edit menu and the Coordinate System... only from the View menu.

### General Configuration

Screenshot of the General Settings dialog
Screenshot of the General Settings dialog

Here you can set global settings which automatic will be saved when you exit &kmplot;. You can set angle-mode (radians and degrees), zoom in and zoom out factors for zooming using &Ctrl; with mouse wheel or the corresponding menu items, and whether to show advanced plot tracing.

### Diagram Configuration

Screenshot of the Diagram Appearance dialog
Screenshot of the Diagram Appearance dialog

You can set the Grid Style to one of four options:

None

  No gridlines are drawn on the plot area

Lines

  Straight lines form a grid of squares on the plot area.

Crosses

  Crosses are drawn to indicate points where x and y have integer values (&eg;, (1,1), (4,2) &etc;).

Polar

  Lines of constant radius and of constant angle are drawn on the plot area.

Other options for the diagram appearance can also be configured:

Axis Labels

  Sets labels for the horizontal and vertical axes.

Axis width:

  Sets the width of the lines representing the axes.

Line width:

  Sets the width of the lines used for drawing the grid.

Tic width:

  Sets the width of the lines representing tics on the axes.

Tic length:

  Sets the length of the lines representing tics on the axes.

Show labels

  If checked, the names of the axes are shown on the plot and the axes' tics are labeled.

Show axes

  If checked, the axes are visible.

Show arrows

  If checked, the axes are displayed with arrows at their ends.

### Colors Configuration

Screenshot of the Colors dialog
Screenshot of the Colors dialog

In the Coords section of the Colors configuration dialog, you can change the colors of the axes, the grid and the background of the main &kmplot; area.

The Default Function Colors control which colors are cycled through when creating new functions.

### Fonts Configuration

Screenshot of the Fonts dialog
Screenshot of the Fonts dialog

Axis labels

  The font used for drawing the axis numbers and x/y labels.

Diagram label

  The font used for drawing diagram labels (&eg;, those showing the plot name or extreme points).

Header table

  The font used for drawing the header when printing a plot.

## &kmplot; Reference

### Function Syntax

Some syntax rules must be complied with:

    		name(var1[, var2])=term [;extensions]

name

  The function name. If the first character is r the parser assumes that you are using polar coordinates. If the first character is x (for instance xfunc) the parser expects a second function with a leading y (here yfunc) to define the function in parametric form.

var1

  The function's variable

var2

  The function group parameter. It must be separated from the function's variable by a comma. You can use the group parameter to, for example, plot a number of graphs from one function. The parameter values can be selected manually or you can choose to have a slider bar that controls one parameter. By changing the value of the slider the value parameter will be changed. The slider can be set to an integer between 0 and 100.

term

  The expression defining the function.

### Predefined Function Names and Constants

All the predefined functions and constants that &kmplot; knows can be shown by selecting Help Predefined Math Functions , which displays this page of &kmplot;'s handbook.

These functions and constants and even all user defined functions can be used to determine the axes settings as well. See .

#### Trigonometric Functions

By default, the trigonometric functions work in radians. However, this can be changed via Settings Configure &kmplot;.

sin(x)
arcsin(x)
cosec(x)
arccosec(x)

  The sine, inverse sine, cosecant and inverse cosecant respectively.

cos(x)
arccos(x)
sec(x)
arcsec(x)

  The cosine, inverse cosine, secant and inverse secant respectively.

tan(x)
arctan(x)
cot(x)
arccot(x)

  The tangent, inverse tangent, cotangent and inverse cotangent respectively.

#### Hyperbolic Functions

The Hyperbolic Functions.

sinh(x)
arcsinh(x)
cosech(x)
arccosech(x)

  The hyperbolic sine, inverse sine, cosecant and inverse cosecant respectively.

cosh(x)
arccosh(x)
sech(x)
arcsech(x)

  The hyperbolic cosine, inverse cosine, secant and inverse secant respectively.

tanh(x)
arctanh(x)
coth(x)
arccoth(x)

  The hyperbolic tangent, inverse tangent, cotangent and inverse cotangent respectively.

#### Other Functions

sqr(x)

  The square x^2 of x.

sqrt(x)

  The square root of x.

sign(x)

  The sign of x. Returns 1 if x is positive, 0 if x is zero, or −1 if x is negative.

H(x)

  The Heaviside Step Function. Returns 1 if x is positive, 0.5 if x is zero, or 0 if x is negative.

exp(x)

  The exponent e^x of x.

ln(x)

  The natural logarithm (inverse exponent) of x.

log(x)

  The logarithm of x to base 10.

abs(x)

  The absolute value of x.

floor(x)

  Rounds x to closest integer less than or equal to x.

ceil(x)

  Rounds x to the closest integer greater than or equal to x.

round(x)

  Rounds x to the closest integer.

gamma(x)

  The gamma function.

factorial(x)

  The factorial of x.

min(x1,x2,...,xn)

  Returns the minimum of the set of numbers {x1,x2,...,xn}.

max(x1,x2,...,xn)

  Returns the maximum of the set of numbers {x1,x2,...,xn}.

mod(x1,x2,...,xn)

  Returns the modulus (Euclidean length) of the set of numbers {x1,x2,...,xn}.

#### Predefined Constants

pi
&pgr;

  Constants representing &pgr; (3.14159...).

e

  Constant representing Euler's Number e (2.71828...).

### Extensions

An extension for a function is specified by entering a semicolon, followed by the extension, after the function definition. The extension can be entered by using the &DBus; method parser addFunction. None of the extensions are available for parametric functions but N and D[a,b] work for polar functions too. For example:

    				f(x)=x^2; A1

will show the graph y=x2 with its first derivative. Supported extensions are described below:

N

  The function will be stored but not be drawn. It can be used like any other user-defined or predefined function.

A1

  The graph of the derivative of the function will be drawn additionally with the same color but less line width.

A2

  The graph of the second derivative of the function will be drawn additionally with the same color but less line width.

D[a,b]

  Sets the domain for which the function will be displayed.

P[a{,b...}]

  Give a set of values of a group parameter for which the function should be displayed. For example: `f(x,k)=k*x;P[1,2,3]` will plot the functions f(x)=x, f(x)=2*x and f(x)=3*x. You can also use functions as the arguments to the P option.

Please note that you can do all of these operations by editing the items in the Derivates tab, the Custom plot range section and the Parameters section in the Functions sidebar too.

### Mathematical Syntax

&kmplot; uses a common way of expressing mathematical functions, so you should have no trouble working it out. The operators &kmplot; understands are, in order of decreasing precedence:

^

  The caret symbol performs exponentiation. &eg;, `2^4` returns 16.

*
/

  The asterisk and slash symbols perform multiplication and division . &eg;, `3*4/2` returns 6.

+
−

  The plus and minus symbols perform addition and subtraction. &eg;, `1+3−2` returns 2.

<
>
≤
≥

  Comparison operators. They return 1 if the expression is true, otherwise they return 0. &eg;, `1 ≤ 2` returns 1.

√

  The square root of a number. &eg;, `√4` returns 2.

|x|

  The absolute value of x. &eg;, `|−4|` returns 4.

±

  Each plus-minus sign gives two sets of plots: one in which the plus is taken, and one in which the minus is taken.&eg;. `y = ±sqrt(1−x^2)` will draw a circle. These, therefore, cannot be used in constants.

Note the precedence, which means that if parentheses are not used, exponentiation is performed before multiplication/division, which is performed before addition/subtraction. So `1+2*4^2` returns 33, and not, say 144. To override this, use parentheses. To use the above example, `((1+2)*4)^2` will return 144.

### Plotting Area

By default, explicitly given functions are plotted for the whole of the visible part of the horizontal axis. You can specify an other range in the edit-dialog for the function. If the plotting area contains the resulting point it is connected to the last drawn point by a line.

Parametric and polar functions have a default plotting range of 0 to 2&pgr;. This plotting range can also be changed in the Functions sidebar.

### Crosshair Cursor

While the mouse cursor is over the plotting area the cursor changes to a crosshair. The current coordinates can be seen at the intersections with the coordinate axes and also in the status bar at the bottom of the main window.

You can trace a function's values more precisely by clicking onto or next to a graph. The selected function is shown in the status bar in the right column. The crosshair then will be caught and be colored in the same color as the graph. If the graph has the same color as the background color, the crosshair will have the inverted color of the background. When moving the mouse or pressing the keys Left or Right the crosshair will follow the function and you see the current horizontal and vertical value. If the crosshair is close to vertical axis, the root-value is shown in the statusbar. You can switch function with the Up and Down keys. A second click anywhere in the window or pressing any non-navigating key will leave this trace mode.

For more advanced tracing, open up the configuration dialog, and select Draw tangent and normal when tracing from the General Settings page. This option will draw the tangent, normal and oscillating circle of the plot currently being traced.

### Coordinate System Configuration

To open this dialog select View Coordinate System... from the menubar.

Screenshot of the Coordinate System dialog
Screenshot of the Coordinate System dialog

#### Axes Configuration

Horizontal axis Range

  Sets the range for the horizontal axis scale. Note that you can use the predefined functions and constants (see ) as the extremes of the range (&eg;, set Min: to `2*pi`). You can even use functions you have defined to set the extremes of the axis range. For example, if you have defined a function `f(x) = x^2`, you could set Min: to `f(3)`, which would make the lower end of the range equal to 9.

Vertical axis Range

  Sets the range for the vertical axis. See Horizontal axis Range above.

Horizontal axis Grid Spacing

  This controls the spacing between grid lines in the horizontal direction. If Automatic is selected, then &kmplot; will try to find a grid line spacing of about two centimeters that is also numerically nice. If Custom is selected, then you can enter the horizontal grid spacing. This value will be used regardless of the zoom. For example, if a value of 0.5 is entered, and the x range is 0 to 8, then 16 grid lines will be shown.

Vertical axis Grid Spacing

  This controls the spacing between grid lines in the vertical direction. See Horizontal axis Grid Spacing above.

### Constants Configuration

To open this dialog select Edit Constants... from the menubar.

Screenshot of the Constants dialog
Screenshot of the Constants dialog

Constants can be used as part of an expression anywhere inside of &kmplot;. Each constant must have a name and a value. Some names are invalid, however, such as existing function names or existing constants.

There are two options that control the scope of a constant:

Document

  If you select the Document checkbox, then the Constant will be saved along with the current diagram when you save it to file. However, unless you have also selected the Global option, the constant will not be available between instances of &kmplot;.

Global

  If you select the Global checkbox, then the Constant's name and value will be written to &kde; settings (where it can also be used by &kcalc;). The constant will not be lost when &kmplot; is closed, and will be available again for use when &kmplot; is started again.

## Command Reference

### Menu Items

Apart from the common &kde; menus described in the Menu chapter of the &kde; Fundamentals documentation &kmplot; has these application specific menu entries:

#### The File Menu

File Export...

  Exports the plotted graphs to an image file in all formats supported by &kde;.

File Print...

  Opens print configuration window. Press the Options >> button then choose the KmPlot Options tab to configure options that are specific for &kmplot;.

File Print Preview

  Shows the preliminary image of the current plot as printed on the current default printer. Press the rightmost button on the toolbar of the print preview window to configure options that are specific for &kmplot;.

#### The Edit Menu

Edit Constants...

  Displays the Constants dialog box. See .

#### The View Menu

The first three items in the menu are related to zooming.

The mouse wheel can also be used as a zoom control. To zoom in or out using the mouse, hold down the &Ctrl; key while you turn the mouse wheel. Each tick increases or decreases the zoom factor by the value defined in the &kmplot; General settings.

&Ctrl;1 View Zoom In

  This tool can be operator in two different manners. To zoom in on a point on the graph, click on it. To zoom in on a specific section of the graph, hold and drag the mouse to form a rectangle, which will be the new axes ranges when the mouse button is released.

&Ctrl;2 View Zoom Out

  The tool can also be used in two different manners. To zoom out and center on a point, click on that point. To fit the existing view into a rectangle, hold and drag the mouse to form that rectangle.

View Fit Widget to Trigonometric Functions

  The scale will be adapted to trigonometric functions. This works both for radians and degrees.

View Reset View

  Resets the view.

View Coordinate System...

  Displays the Coordinate System dialog box. See .

View Show Sliders

  Toggles the visibility of the slider dialog. In the dialog move a slider to change the parameter of the function plot connected to it.

  Enable this on the Function tab and select one of the sliders to change the parameter value dynamically. The values vary from 0 (left) to 10 (right) by default, but can be changed in the slider dialog.

  For a small tutorial see Using Sliders.

#### The Tools Menu

This menu contains some tools for the functions that can be useful:

Tools Calculator

  Opens the Calculator dialog.

Tools Plot Area...

  Select a graph and the values of the horizontal axis in the new dialog that appears. Calculates the integral and draws the area between the graph and the horizontal axis in the range of the selected values in the color of the graph.

Tools Find Minimum...

  Find the minimum value of the graph in a specified range.

Tools Find Maximum...

  Find the maximum value of the graph in a specified range.

#### The Help Menu

&kmplot; has a standard &kde; Help with one addition:

Help Predefined Math Functions...

  Opens this handbook with a list of the predefined function names and constants that &kmplot; knows.

## Scripting &kmplot;

You can write scripts for &kmplot; using &DBus;. For example, if you want to define a new function `f(x)=2sin x+3cos x`, set its line width to 20 and then draw it, you type in a console:

`qdbus org.kde.kmplot-PID /parser org.kde.kmplot.Parser.addFunction "f(x)=2sin x+3cos x" ""` As a result, the new function's id number will be returned, or -1 if the function could not be defined.

`qdbus org.kde.kmplot-PID /parser org.kde.kmplot.Parser.setFunctionFLineWidth ID 20` This command sets the function with the id number ID the line width to 20.

`qdbus org.kde.kmplot-PID /view org.kde.kmplot.View.drawPlot` This command repaints the window so that the function get visible.

A list of the available functions:

/kmplot org.kde.kmplot.KmPlot.fileOpen url

  Load the file `url`.

/maindlg org.kde.kmplot.MainDlg.isModified

  Returns true if any changes are done.

/maindlg org.kde.kmplot.MainDlg.checkModified

  If there are any unsaved changes, a dialog appears to save, discard or cancel the plots.

/maindlg org.kde.kmplot.MainDlg.editAxes

  Opens the coordinate system edit dialog.

/maindlg org.kde.kmplot.MainDlg.toggleShowSlider

  Shows/hides parameter slider window.

/maindlg org.kde.kmplot.MainDlg.slotSave

  Saves the functions (opens the save dialog if it is a new file).

/maindlg org.kde.kmplot.MainDlg.slotSaveas

  The same as choosing File Save As in the menu.

/maindlg org.kde.kmplot.MainDlg.slotPrint

  Opens the print dialog.

/maindlg org.kde.kmplot.MainDlg.slotResetView

  The same as choosing View Reset View in the menu.

/maindlg org.kde.kmplot.MainDlg.slotExport

  Opens the export dialog.

/maindlg org.kde.kmplot.MainDlg.slotSettings

  Opens the settings dialog.

/maindlg org.kde.kmplot.MainDlg.slotNames

  Shows the predefined math functions in the handbook.

/maindlg org.kde.kmplot.MainDlg.findMinimumValue

  The same as choosing Tools Minimum Value... in the menu.

/maindlg org.kde.kmplot.MainDlg.findMaximumValue

  The same as choosing Tools Maximum Value... in the menu.

/maindlg org.kde.kmplot.MainDlg.graphArea

  The same as choosing Tools Plot Area in the menu.

/maindlg org.kde.kmplot.MainDlg.calculator

  The same as choosing Tools Calculator in the menu.

/parser org.kde.kmplot.Parser.addFunction f_str0 f_fstr1

  Adds a new function with the expressions `f_str0` and `f_str1`. If the expression does not contain a function name, it will be auto-generated. The id number of the new function is returned, or -1 if the function could not be defined.

/parser org.kde.kmplot.Parser.removeFunction id

  Removes the function with the id number `id`. If the function could not be deleted, false is returned, otherwise true.

/parser org.kde.kmplot.Parser.setFunctionExpression id eq f_str

  Sets the expression for the function with the id number `id` to `f_str`. Returns true if it succeed, otherwise false.

/parser org.kde.kmplot.Parser.countFunctions

  Returns the number of functions (parametric functions are calculated as two).

/parser org.kde.kmplot.Parser.listFunctionNames

  Returns a list with all functions.

/parser org.kde.kmplot.Parser.fnameToID f_str

  Returns the id number of `f_str` or -1 if the function name `f_str` was not found.

/parser org.kde.kmplot.Parser.functionFVisible id

  Returns true if the function with the ID `id` is visible, otherwise false.

/parser org.kde.kmplot.Parser.functionF1Visible id

  Returns true if the first derivative of the function with the ID `id` is visible, otherwise false.

/parser org.kde.kmplot.Parser.functionF2Visible id

  Returns true if the second derivative of the function with the ID `id` is visible, otherwise false.

/parser org.kde.kmplot.Parser.functionIntVisible id

  Returns true if the integral of the function with the ID `id` is visible, otherwise false.

/parser org.kde.kmplot.Parser.setFunctionFVisible id visible

  Shows the function with the ID `id` if `visible` is true. If `visible` is false, the function will be hidden. True is returned if the function exists, otherwise false

/parser org.kde.kmplot.Parser.setFunctionF1Visible id visible

  Shows the first derivative of the function with the ID `id` if `visible` is true. If `visible` is false, the function will be hidden. True is returned if the function exists, otherwise false.

/parser org.kde.kmplot.Parser.setFunctionF2Visible id visible

  Shows the second derivative of the function with the ID `id` if `visible` is true. If `visible` is false, the function will be hidden. True is returned if the function exists, otherwise false.

/parser org.kde.kmplot.Parser.setFunctionIntVisible id visible

  Shows the integral of the function with the ID `id` if `visible` is true. If `visible` is false, the function will be hidden. True is returned if the function exists, otherwise false.

/parser org.kde.kmplot.Parser.functionStr id eq

  Returns the function expression of the function with the ID `id`. If the function not exists, an empty string is returned instead.

/parser org.kde.kmplot.Parser.functionFLineWidth id

  Returns the line width of the function with the ID `id`. If the function not exists, 0 is returned.

/parser org.kde.kmplot.Parser.functionF1LineWidth id

  Returns the line width of the first derivative of the function with the ID `id`. If the function not exists, 0 is returned.

/parser org.kde.kmplot.Parser.functionF2LineWidth id

  Returns the line width of the second derivative of the function with the ID `id`. If the function not exists, 0 is returned.

/parser org.kde.kmplot.Parser.functionIntLineWidth id

  Returns the line width of the integral of the function with the ID `id`. If the function not exists, 0 is returned.

/parser org.kde.kmplot.Parser.setFunctionFLineWidth id linewidth

  Sets the line width of the function with the ID `id` to `linewidth`. True is returned if the function exists, otherwise false.

/parser org.kde.kmplot.Parser.setFunctionF1LineWidth id linewidth

  Sets the line width of the first derivative of the function with the ID `id` to `linewidth`. True is returned if the function exists, otherwise false.

/parser org.kde.kmplot.Parser.setFunctionF2LineWidth id linewidth

  Sets the line width of the second derivative of the function with the ID `id` to `linewidth`. True is returned if the function exists, otherwise false.

/parser org.kde.kmplot.Parser.setFunctionIntLineWidth id linewidth

  Sets the line width of the integral of the function with the ID `id` to `linewidth`. True is returned if the function exists, otherwise false.

/parser org.kde.kmplot.Parser.functionParameterList id

  Returns a list with all the parameter values for the function with the ID `id`.

/parser org.kde.kmplot.Parser.functionAddParameter id new_parameter

  Adds the parameter value `new_parameter` to the function with the ID `id`. True is returned if the operation succeed, otherwise false.

/parser org.kde.kmplot.Parser.functionRemoveParameter id remove_parameter

  Removes the parameter value `remove_parameter` from the function with the ID `id`. True is returned if the operation succeed, otherwise false.

/parser org.kde.kmplot.Parser.functionMinValue id

  Returns the minimum plot range value of the function with the ID `id`. If the function not exists or if the minimum value is not defined, an empty string is returned.

/parser org.kde.kmplot.Parser.functionMaxValue id

  Returns the maximum plot range value of the function with the ID `id`. If the function not exists or if the maximum value is not defined, an empty string is returned.

/parser org.kde.kmplot.Parser.setFunctionMinValue id min

  Sets the minimum plot range value of the function with the ID `id` to `min`. True is returned if the function exists and the expression is valid, otherwise false.

/parser org.kde.kmplot.Parser.setFunctionMaxValue id max

  Sets the maximum plot range value of the function with the ID `id` to `max`. True is returned if the function exists and the expression is valid, otherwise false.

/parser org.kde.kmplot.Parser.functionStartXValue id

  Returns the initial x point for the integral of the function with the ID `id`. If the function not exists or if the x-point-expression is not defined, an empty string is returned.

/parser org.kde.kmplot.Parser.functionStartYValue id

  Returns the initial y point for the integral of the function with the ID `id`. If the function not exists or if the y-point-expression is not defined, an empty string is returned.

/parser org.kde.kmplot.Parser.setFunctionStartValue id x y

  Sets the initial x and y point for the integral of the function with the ID `id` to `x` and `y`. True is returned if the function exists and the expression is valid, otherwise false.

/view org.kde.kmplot.View.stopDrawing

  If &kmplot; currently is drawing a function, the procedure will stop.

/view org.kde.kmplot.View.drawPlot

  Redraws all functions.

## Credits and License

&kmplot;

Program copyright 2000-2002 Klaus-Dieter Möller &Klaus-Dieter.Moeller.mail;

### Contributors

- CVS: &Robert.Gogolok; mail@robert-gogoloh.de

- Porting &GUI; to &kde; 3 and Translating: &Matthias.Messmer; &Matthias.Messmer.mail;

- Various improvements: Fredrik Edemar f_edemar@linux.se

- Porting to Qt 4, UI improvements, features: David Saxton david@bluehaze.org

Documentation copyright 2000--2002 by Klaus-Dieter Möller &Klaus-Dieter.Moeller.mail;.

Documentation extended and updated for &kde; 3.2 by &Philip.Rodrigues; &Philip.Rodrigues.mail;.

Documentation extended and updated for &kde; 3.3 by &Philip.Rodrigues; &Philip.Rodrigues.mail; and Fredrik Edemar f_edemar@linux.se.

Documentation extended and updated for &kde; 3.4 by Fredrik Edemar f_edemar@linux.se.

Documentation extended and updated for &kde; 4.0 by David Saxton david@bluehaze.org.

&underFDL; &underGPL;

&documentation.index;