Difference between revisions of "Scilab/C4/Calling-User-Defined-Functions-in-XCOS/English"

1. To use the scifunc block in Xcos
2. To use MUX block to draw multiple plots
3. To call functions having multiple inputs and outputs

1. Basic knowledge of Scilab.
2. Basic knowledge of Xcos
3. If not, for relevant tutorials please visit spoken hyphen tutorial dot org

y=a^2;

endfunction

function space y is equal to squareit open bracket a close bracket

Press the enter key and type

y is equal to a raise to 2

put a semicolon in the end

The name of the function is squareit

This function will do the job of squaring the variable a.

It will store the result in y.

I will save this file with file name squareit and extension .sci

Here we are following the convention of saving functions in .sci format.

Now, type Xcos and press Enter.

Two windows will open

A palette browser and an untitled Xcos window.

This will access the function squareit created just now.

This can be done by using scifunc block.

Click on User-Defined function in the pallet browser.

Locate the block scifunc_block_m in this section.

Drag and drop it in the untitled Xcos window.

I will use the Zoom button as you see.

Now double click on the scifunc block to configure it.

A window named Scilab multiple values request will open

This window will allow you to change the number of input and output ports of the scifunc block.

Hence, we will keep the settings unchanged.

Click on Ok.

In the text box, type the function name along with input and output variables.

This function will be called by the scifunc block

edit the default function name.

Type y1 equal to squareit open bracket u1 close bracket

Cick on OK.

Cick on OK.

Keep clicking on Ok in the subsequent 3 windows that will appear.

The scifunc block is now been configured.

In the palette browser window, click on Sources section.

Drag and drop the Sinusoid Generator block in the untitled Xcos window.

In the palette browser window, click on Sinks section.

Drag and drop the CScope block in the untitled Xcos window.

Place it away from scifunc block, for convenience.

This is an event input

we need an event generator block.

Drag and drop the clock underscore c block in the untitled Xcos window.

But we want to plot both the input and output variables in a single plot window.

This block will multiplex two inputs and generate output on one output port.

Drag and drop the MUX block in the untitled Xcos window.

Now let us connect the blocks together.

Connect the output port of Sinusoid generator block to the input port of scifunc block

We have to connect the Sinusoid generator block to the MUX.

Click on the upper input port of the MUX block.

Release the mouse button or click once to create a link between these two blocks.

We can change the frequency, magnitude and phase of the sinusoid generator block.

The configuration window will open.

We will keep the magnitude and frequency as 1 and phase as 0

Double click on the CScope block to open its configuration window.

Make a mental note of this value.

click on OK

Double click on the block to open its configuration window.

Click on OK

On the menu bar of the untitled Xcos window click on the Simulation tab.

Now click on Setup from the drop down menu.

Hence, put the value of Final integration time as 10.

I will save it as squareit.xcos

Choose a desired directory to save the Xcos diagram.

Click on OK

This means that we should first load the squareit function before we execute the xcos diagram.

This will load the squareit function.

Now we can execute the Xcos diagram.

Click on the Start button available on the menu bar of Xcos window

A graphic window will appear.

Input sine wave in black color and output sine wave in green color.

Hence, the output sine wave has been shifted to the positive axis.

Close the plot window

Edit the squareit function to have two input and output variables.

Edit the output variable as open square bracket y comma z close the square bracket .

Edit the input variables as open bracket a comma b close bracket

Edit the main function line as

y is equal to b plus a raise to two

put a semicolon in the end

Go to next line by pressing enter key and type

z is equal to 0.5 multiplied by a

put a semicolon in the end

Save the file

Double click on the scifunc block to configure it.

In the input port size field, put a semi colon after 1 comma 1 and type 1 comma one again

Click on Ok

[y1,y2]=squareit(u1,u2)

In the text box,

Put a comma after y1 and type y2.

Put y1 and y2 in square brackets

Now put a comma after u1 and type u2

Click on OK

Keep on clicking Ok in the subsequent 3 windows that will appear.

The scifunc block has now been configured.

In the sources section, drag and drop the Constant underscore m block in the xcos window.

Close it near the sinusoid generator block.

The default value of this block is 1.

Keep it unchanged.

Change the input port size to 3

Click on OK

Connect the lower output port of the scifunc block to the lower input port of MUX block

Click on File and choose Save to save the xcos file.

This will load the squareit function.

Now we can execute the Xcos diagram.

A graphic window will appear.

Input sine wave in black color,

output sine wave in green color and

the amplitude scaled input in red colour

We also get the amplitude scaled of the input sine wave, as expected

Close the plot window

In this tutorial we learnt,

1. To write a squaring function in Scilab
2. To use the scifunc block in Xcos
3. To use MUX block to draw multiple plots
4. To call functions having multiple input and output

• It summarizes the Spoken Tutorial project

• If you do not have good bandwidth, you can download and watch it

• Conducts workshops using spoken tutorials

• Gives certificates for those who pass an online test

• For more details, please write to contact at spoken hyphen tutorial dot org

• It is supported by the National Mission on Education through ICT, MHRD, Government of India

• More information on this Mission is available at

• spoken hyphen tutorial dot org slash NMEICT hyphen Intro

Hope you found this tutorial useful.

This is Anuradha Amruthkar from IIT Bombay signing off.

Thank You.