Open source cross-platform software of geometry, analysis and simulation - Yves Biton

MathGraph32 Java : FAQ

publication Saturday 1 October 2011.

How to get help on MathGraph32 ?

How to know the way a figure has been created ?

Why no right click to modify an object ?

How to modify the line style or color of a graphical object ?

How to compute the area of a triangle or a polygon ?

How to graph function curves ?

How to graph a function curve on an interval ?

How to print a figure with respect of the dimensions in centimeters ?

How to display the coordinates of a point in a frame ?

How to compute the maximum or the minimum of a function on an interval ?

How to work in a frame ?

How to scale the axes of a frame ?

How to display a numerical value on a figure ?

How to make a numerical value vary ?

How to modify a numerical object already created ?

How to modify a graphical object already created ?

How to make a linked point become a free point ?

How to make a free point become a linked point ?

How to link a display to a point ?

How to free a display linked to a point ?

I have just created a cursor and I don’t manage to change it’s size or it’s position on the figure. How to do ?

I want to modify the formula of a calculation or a function and the modification is not allowed. Why ?

How to get help on MathGraph32 ?

To launch the integrated html help, just press F1 key.

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[How to know the way a figure has been created ?

To see the protocol of the figure, press F5 key or use icon.

All the objects are fully described in a list and you can modify or reclassify them.

Click on icon to swich to the followingobject.

Click on icon to switch to the preceeding object.

Click on icon to switch to the last object.

Click on icon to switch to the last object.

The right arrows allow to reclassify the relative order of objects.

Click on icon to delete the current object and all the depending objects.

Click on icon to destroy the current object and all the following objects.

When the current object was created through a dialog bos, the icon make this dialog box pop up.

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Why is’nt it possible to right click for an object modification ?

There are reasons for this choice.

Let’s have an example : A figure has been created with many black segments. We would like to turn them red.

With the usual ergonomy Right click - Object inspectoryou should right click on each object the for each object modify the color which is boresome.

MathGraph32 has chosen tools to modify objects.

Tool allows to modify the line style and color of an object (see ici). So, to change the color of the segments, you will choose the red color in the color palette and then click on each one after activation of tool .

Tool allows to modify an graphical object (if created via a dialog box.

Tool allows to modify a numerical object .

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How to modify the line style or color of a graphical object ?

First click on the chosen color in the color palette and on the chosen line style in the style palette.

Then click on the object to give it the chosen color and line style.

Here are the different palettes :

: The color palette. Click on the ellipsa to choose a personalized color.

: The line style palette.

: The point style palette.

:The segment mark style palette.

: The angle mark style palette.

: The fill style palette for surfaces. The default fill style is the transparency fill style style de remplissage par transparence . Transparency can be modified with the cursor lying under the color palette.

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How to compute the area of a triangle or a polygon ?

To compute the area of a triangle, you must first create a polygon with tool .

Then click on icon of polygon area measure and click on the polygon polygone. A dialog box will ask you for a name to be affected to this area.

In the same way you can compute the area of a some polygon.

To be noticed : This measure will not be accurate if the polygon is crossed..

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How to graph function curves ?

To graph a function curve, the easiest way is to create a new figure with a frame with icon .

The use icon .A dialog box pops up.

Let the check box Draw curvechecked if you wand the curve to be graphed immediatly.

To modify the formula of a function f, use icon or press F6 key.

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How to graph a function curve on an interval ?

To graph a function on an interval [a;b] or [a;$\infty$[ or ]-$\infty$;a], click on icon
but uncheck the check box Draw curve.

For instance to graph a function on interval[$-\pi$;$\pi$], click on icon .
A dialog box pops up as this one. Fill it as follows.

.

Once the dialog box validated, the curve appears.

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How to print a figure with respect of the dimensions in centimeters ?

To print a figure with respect of the dimensions in centimeters, the figure must have an unity length.

When you create a new figure (without a frame), a segment [UV ]is created in the top left corner of the figure. This segment’s length is the unity of the figure

When you create a new figure with a frame (O,I,J) (icon ), OI length is tue unity of the figure.

Let us say you have created a figure with a triangle of dimensions 3, 5 et 6.

Use icon A dialog box pops up as this one :

Your figure will be saved in a png file so that the length unity will be exactly 1 cm.

To get this figure printed, you must use your word processor. insert in your document the png image file you saved before.

Printing this document with your word processor, you will get exactly the dimensions expected.

To be noticed : : If your figure is too big to fit in the page, your word processor will reduce it and you won’t get the dimensions expected when printing.

Remark : In the dialog box, if you enter 0.5 in the field Unity length in centimeter then your figure will be exported with a ratio of one half.

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How to display the coordinates of a point in a frame

The most simple way is to use a predefined construction.

Let us say you have created a figure with a frame and a point M you want the coordinates to be measured and displayed.

Use menu item Constructions - Implement predefined construction and open directory Measures. Then click on the construction named Point Coordinates Measure With Display.

You are asked to click on the point : click on M.

You are told that numerical objects have been created and asked whether you want to modify their names. If you accept you will see that M x aand y coordinates have been measured. You can rename them xM and yM if you want.

You will see on the figure a display of x and y. This display is a LaTeX display linked to point M. You can get it modified with tool . You can also free this display with menu item Modify - Link deletion - between point and object.

The LaTeX code of this display is :\left( {\Val{xM,2}; \Val{yM,2}} \right).

If you replace this code with \left( {\Val{xM,1}; \Val{yM,1}} \right), the coordinates will be displayed with one digit instead of two.

Remark : : With a predefined construction you can also measure and display the coordinates of a vector in a frame.

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How to compute the maximum or the minimum of a function on an interval ?

You can compute the maximum of a function on an interval [a;b] using menu item Calculation - New real calculation - Maximum of a function. The functionmust be derivble on this interval and must admit a maximum on this interval.

Let us have an example. We want to compute on interval [0;$\pi$] of the maximum of function f défined by $f(x)=\sin(x)-\frac{1}{4}x$.

First create a new figure with an orthonormal frame with icon .Make sure the angle unity of this figure is radian (menu item Options - Current figure, tab Angle unity)..

Use icon to create function f and graph it. Fill in the dialog box as shown below.

Use menu item Calculation - New real calculation - Maximum of a function. Fill the dialog box as below.

If you click on icon (key board shortcut F6 you will see that MaathGraph32 created a new calculus named maxf containing the x-coordinate of the point where the maximum of f is reached on interval [0; \pi] .

Nox use icon . In the field x-coordinate enter maxf (You can use button Values. In the field y-coordinate enter f(maxf) then validate.

You can now see a point at the top of the curve on interval [0;$\pi$].

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How to work in a frame ?

Starting from a new figure.

To start a new figure with a frame, just use icon (or menu item File- New figure with - Frame).

If you check the Frame with vectors checkbox, two vectors will be created on each axis.

You can ask for a frame orthonormal, orthogonal, oblique or oblique with equal lengths unities. It is also possible to choose a kind of grid.

You may add new frames to a figure (as many as you want).

For this, use tool (or menu item Create - Frame).

Click first on the origin then on two other points. A dialog pops up allowing you to choose the frame characteristics

To modify a frame or its grid, just use menu item Modify - Frame.

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How to scale the axes of a frame ?

You can scale frame axis with menu item Modify- Add scales to a frame.

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How to display a numerical value on a figure ?

To display a numerical value already created or measured, use icon for a free display or icon for a display linked to a point.

For a free display, click on the chosen spot in the figure.

For a display linked to a point, click first on the point the display will be linked to.

A dialog box pops up. You can choose the value to be displayed, the number of digits, if the background must be erased (you can choose the background color) and possibly a frame surrounding the display.

Yo can also use tool to create a LaTeX display which will contain a dynamic display of value (only for calculations and variables, not measures).

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How to make a numerical value vary ?

The two main way of getting numerical value vary are :

The use of a cursor with icon

Example : We wand to create a circle with a variable radius.

Start from a new figure with icon

Click first on icon (cursor creation).

Click on the top left corner of the figure to indicate the spot of the left edge of the cursor.

Then fill in the dialog box as shown below :

Use icon to create a free point at the center of the figure.

Then use icon , click on the free point and enter R as radius for the circle in the dialog box.

A variable creation with menu item Calculation - Newvariable keyboard shortcut Ctrl - V).

Example : We want to graph the line of equation $ax+by=a+b$ where a et b are two variables.

First create a new figure with an orthonormal frame (tool ).

Create a new variable with menu Calculation - New variable or keyboard shortcut Ctrl V..

Fill in the dialog box as below :

A little dialog box appears on the right botton of the figure with buttons allowing to make the variable vary.

In the same way create a variable named b ranging from -5 to 5 with a step value of 0.5 and 3 for current value. Don’t forget to check the Associatied dialog checkbox.

Now click on to create a line by an equation.

Fill in the dialog box as below and validate :.

You can now make a and b vary by clicking on buttons + and - de of the little dialog box.

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How to modify a numerical object already created ?

To modify a numerical object (for instance calculation, function, recurrent sequence) use tool (keybord shortcut F6).

A dialog box lists all the numerical objects created that can be modified. Select the object you want to modify then click on button Modify (or double-click the value in the list). A new dialog box pops up allowing the object modification.

You can also :

Delete the object with a clik on button Delete.

Reclassify an object as far as possible towards the beginning in the list of created objects.

Reclassify an object as far as possible towards the end in the list of created objects..

Create a new calculation with a click on Calculation creation

Create a new function of a real variable with a click on Create function.

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How to modify a numerical object already created ?

To modify the color or the graphic style of an object, use icon after choosing the style and color of the object in the palettes at the right of the MathGraph32 window.

When a graphical object was created vi a dialog box (for instance calculation, function, recurrent sequence, image through a rotation rotation, dilation ...) use tool .

A dialog box will popup allowing you to modify the object.

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How to make a linked point become a free point ?

For this, use menu item Modify- Link deletion - Between point and object the click on the point.

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How to make a free point become a linked point ?

For this, use menu item Modifier- Link creation - Between point and object, click on the free point then click on the object you want it to be linked to.

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How to link a display to a point ?

After a display (text, LaTeX, value display, macro) creation, it is possible to link the display to a point.

For this, use menu item Modify - Link creation - Between display and point click on the dispaly then on the point you want the display to be linked to.

Once linked to the point point, the display will follow the point when this one will move. You may also move the relative position of the dispaly with tool .

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How to free a display linked to a point ?

For this, use menu item Modify - Link deletion - Between display and point. Displays which are linked to a point are blinking. Click on the display ou want to free.

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I have just created a cursor and I don’t manage to change it’s size or it’s position on the figure. How to do ?

In the cursor creation dialog box, the checkbox Pin nup extremeties is checked by default. You can uncheck this chekbox.

But you may want to move the cursor after its creation.

Then use tool to unpin a point.

To move the cursor, unpin the left extremity , upin the left extremity the move it with with capture tool .

To make the cursor bigger, unpin the right extremity the move it with tool .

It is better te re-pin the points after with tool

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I want to modify the formula of a calculation or a function and the modification is not allowed. Why ?

The basic rule is that, to be created, an object must use only the objects created before. So probably when modifying your object you tried to use an object created after the object you want to modify.

Then you must use object reclassification before the modifiction of the formula.

Let us say you first created calculus named R containing 2 as formula. The you want the formula to be 2*AB where AB is a length meaured after the calculus creation.

Two possibilities :

Reclassify calculus R towards the end of the objects list. Use icon (keyboard shortcut F6). You can also use the figure protocol (keyboard shortcut F5)

Reclassify length measure RAB towards the end of the objects list. Use icon (keyboard shortcut F6). You can also use the figure protocol (keyboard shortcut F5).

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