how to define a function handle if i need to define a function from R^n to R?

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San Carlo 2020-12-16

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评论： James Tursa 2020-12-16

Hello! I'm sorry for my dumb question but i need to define a function f(x) from R^n to R where n is very large (say n=1000) but if I use the command f = @(x) = sum(1/2*x(i,:)^2+x(i,:)) it gives me error if I try to insert a x wich belongs to R^n and it only works if I put a scalar value. What's the correct sintex? How do I define this function?

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James Tursa 2020-12-16

I am confused about what you want. Can you provide a short example of input and desires output? E.g., what would be the desired output for the following inputs:

x = reshape(1:24,2,3,4);

x = reshape(1:120,2,3,4,5);

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Answer 1

Star Strider 2020-12-16

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I am not certain what you are doing or what result you want.

Try these to see which one gives you what you want:

fr = @(x) sum(1/2*x(:).^2+x(:),2);           % Use Element-Wise exponentiation (.^) & Force Column Vectors To Sum Across Columns
fc = @(x) sum(1/2*x(:).^2+x(:));             % Use Element-Wise exponentiation (.^) & Force Column Vectors To Sum Down Columns
x = rand(5,1);
yr = fr(rx);
yc = fc(x);

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