Multiply two griddedInterpolant functions

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I have some data and I have interpolated them using the function griddedInterpolant. Now, let's suppose I end up with f and g from the previous interpolation. What I want to do now is fun = f*g. I can I do that?

Accepted Answer

Bjorn Gustavsson
Bjorn Gustavsson on 25 Oct 2021
If you have 2 functions f(x,y) and g(x,y) you can evaluate the product on your selected grid-points and multiply them:
fx_at_xy = f(x,y).*g(x,y);
or you can create a function that multiplies the two:
f_times_g = @(x,y) f(x,y).*g(x,y);
and use that one - this should (at least ought to) be more convenient when for example integrate over some region in the x-y-plane.
  1 Comment
Anita Capelli
Anita Capelli on 25 Oct 2021
I couldn't do it like this. So I changed and I used instead of griddedInterpolant interp1 creating an handle function. Therefore, supposing to have data_x = [], data_y = [], I created f = @(x) interp1(data_x,data_y,x). The same for g. How should I multiply them? I was doing
h = @(x) f(x).*g(x)
but it says Array indices must be positive integers or logical values.

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