# I have a problem in MATLAB Simulink.

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Shiv Nileshkumar Matliwala
on 13 Sep 2022

Edited: Shiv Nileshkumar Matliwala
on 16 Sep 2022

So, I want to build the simulink model with "Matlab funcion" as a block. Which has input and output. Now, I have taken sine wave as an input. so "u = sin wave" here I have used "Sin wave" block. Now in function block i have added function as below,

I have attched screenshot of simulink model.

function y = fcn(u)

t_span = 5

y = u(t<t_span);

Here in order to calculate the value of y, I need time "t". So that I can compare it with "t_span". So, When I try to write parameter into "fcn(u)" as "fcn(u(t))" it creates another input port in function block.

So, My question is how can i use internal parameter "t" of sine wave block as a variable for different equations ??

Thank you.

##### 4 Comments

Sam Chak
on 13 Sep 2022

@Shiv Nileshkumar Matliwala, Before answering your queries, here is a straightforward request:

- Please sketch the desired output waveform of the MATLAB Function block.
- If you know the equation of the desired output, please display it here.

### Accepted Answer

Aditya
on 16 Sep 2022

Edited: Aditya
on 16 Sep 2022

Hi,

I understand that you are trying to get the parameters from which sine wave is calculated, particularly time “t”.

The sine wave output is calculated from the following formula:

y = amplitude*sin(frequency*t + phase) + bias;

amplitude, frequency, phase, and bias are all sine wave block parameters that are fixed.

For getting the time “t”, you can use the Clock block as discussed in Display and provide simulation time - Simulink (mathworks.com).

Here is an example of using a MATLAB function block to generate same waveform as a sine wave. You can see that the function uses the internal parameters of the sine wave block. You can have an extra input to your MATLAB function block from the clock block.

function y = fcn(t)

frequency = 1; %Same as the sine wave block parameter

amplitude = 1; %Same as the sine wave block parameter

bias = 0; %Same as the sine wave block parameter

phase = 0; %Same as the sine wave block parameter

y = amplitude*sin(frequency*t + phase) + bias;

end

##### 3 Comments

Aditya
on 16 Sep 2022

Edited: Aditya
on 16 Sep 2022

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