# how take a mathematical function from user

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Ahmed Amin 2021년 5월 8일
댓글: Ahmed Amin 2021년 5월 8일
How can i take F and G from the user to use them in a function if i have F=@(x,y) x./y;
and G=@(x) sqrt(x.^2+1); ?
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Ahmed Amin 2021년 5월 8일
ok but how can i use feval in my case ?

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### 답변(1개)

Steven Lord 2021년 5월 8일
What do you mean when you say you want "the user to enter" the function in your comment?
Do you want the user to have to pass some thing into your function that lets your function call a function of their choosing? If so you want your user to define a function handle (which could be an anonymous function.)
f1 = @(x, y) x./y; % anonymous function
z1 = integral2(f1, 0, 1, 1, 2) % integral2 will call the function f with inputs of its choice
z1 = 0.3466
f2 = @sin; % regular function handle
z2 = integral(f2, 0, pi)
z2 = 2.0000
Or do you want to have the user enter the text of a function in say an edit box in a dialog or UI? In that case you should use str2func.
s = 'x./y';
f3 = str2func(['@(x, y)' s]); % make an anonymous function which is a function handle
z3 = integral2(f3, 0, 1, 1, 2)
z3 = 0.3466
% or
f4 = str2func('sin'); % make a regular function handle
z4 = integral(f4, 0, pi)
z4 = 2.0000
Or did you have a different meaning in mind? In this case, please explain what you want to do in more detail.

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