# Hello everyone please I have a problem. How to declare a function with two variables in MATLAB and plot the evolution according to one variable after having fixed the other ??

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Thomas TJOCK-MBAGA on 18 May 2022
Hello everyone please I have a problem. How to declare a function with two variables in MATLAB and plot the evolution according to one variable after having fixed the other ??? For example I declare y = exp (-0.1xt + x) x sin (3x) after first declaring the variables x and t, I would like to plot the evolution of y as a function of x for t = 1, 2 and 3. Thank you Best regards !!!
I Wrote the following code
clear aller Close all x = linspace (0, 1, 25) t= linspace (0, 5, 500) y= exp (-0.1xt + x) x sin (3x) plot (x, c(1,:), 'bo', x,c(2,:), 'mo', x, c(3,:), 'co')
When on run the code the message issu Matrix dimension must agree

Michal on 18 May 2022
Also, due to Matlab's explicit matrix expansion (I think that's waht they call it), you can simply use the dimensions to cereate your vectors for the different t values, like this:
x = 1:100;
t = [15;20;25]; % a different dimension from x
y = exp(-0.1*x.*t+x).*x*3.*sin(x); % each row of y is y=f(x) for the corresponding t
plot(y');
Is this what you were after?
Thomas TJOCK-MBAGA on 18 May 2022
I try it but the code doesn't run

Sam Chak on 18 May 2022
Because one is 1x25, and the other is 1x500. Now both are 1x100.
x = linspace(0, 1, 100);
t = linspace(0, 5, 100);
y = exp(-0.1*x.*t + x).*x.*sin(3*x);
plot(x, y)
##### 2 CommentsShowHide 1 older comment
Thomas TJOCK-MBAGA on 18 May 2022
I want you to plot the curves for t = 1, t = 2 and t = 3. Thanks

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