# I want to enter a mathematical function as an argument to a function

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Paul on 27 Sep 2022
Commented: Paul on 27 Sep 2022
Hello, to be more precise: I want to call in my program a function that I have created and that allows to display the plot of a mathematical function, so I want to enter in argument of this function a mathematical expression that can be for example "sin(t) or 4*t+9". Knowing that the interval "t" is defined inside the function.
My problem is the following, when I launch the program it says to me that it does not know "t", logic since at the moment or the program reads it it is not yet defined.
How to solve this problem?
main program
plot_compare(sin(t) , 5 ,20);
secondary program
function plot_compare(f,N,M)
t = [];
S_N = [];
t = linspace(-pi ,pi ,M);
b = linspace (0,10,N);
S_N = sinesum(t,b);
plot(t,f,t,S_N);
end

Stephen23 on 27 Sep 2022
Edited: Stephen23 on 27 Sep 2022
The simple approach using a function handle:
plot_compare(@sin , 5 ,20);
plot_compare(@(t) 4*t+9 , 5 ,20);
function plot_compare(fnh,N,M)
t = linspace(-pi ,pi ,M);
b = linspace (0,10,N);
%S_N = sinesum(t,b);
plot(t,fnh(t));
end
Paul on 27 Sep 2022
Thank you
I had found the beginning of a solution on the internet with the handle function but I understood where my mistake was, I must specify in the plot function that my function "f" must be plotted as a function of "t" so it's
plot(t,f(t))
and not
plot (t,f)
Thank you again