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Why am I not getting a vector output?

Asked by Dawid Brits on 17 Oct 2019
Latest activity Commented on by Dawid Brits on 17 Oct 2019
Hi All,
Ive writen this function that computes the gradient vector for a function, but it only gives me a single value output. What am I doing wrong?
gradlandscape(3, 3);
function [retx, rety] = gradlandscape(x, y)
h = 0.1;
retx = (landscape(x+h, y)-landscape(x-h, y))/(2*h);
rety = (landscape(x, y+h)-landscape(x, y-h))/(2*h);
function M = landscape(x, y)
M = H1(x, y) + H2(x, y);
function h1 = H1(x, y)
R1 = 2;
s1 = [-2;2];
n1 = 2;
h1 = (1./(1+(R1./sqrt((x-s1(1)).^2+(y(:)-s1(2)).^2)).^n1));
end
function h2 = H2(x, y)
R2 = 1;
s2 = [3;-1];
n2 = 1;
h2 = (1./(1+(R2./sqrt((x-s2(1)).^2+(y(:)-s2(2)).^2)).^n2));
end
end
end

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1 Answer

Answer by Adam Danz
on 17 Oct 2019
Edited by Adam Danz
on 17 Oct 2019
 Accepted Answer

That's because you're only asking for a single output (by default). If you want both outputs, you must include two outputs in your call to the function.
[retx, rety] = gradlandscape(3, 3)
If the intention of the function was to produce a single output that is a 1 x 2 vector instead of two scalar outputs, then you'll need to change the function like this:
function retxy = gradlandscape(x, y)
h = 0.1;
retxy(1) = (landscape(x+h, y)-landscape(x-h, y))/(2*h);
retxy(2) = (landscape(x, y+h)-landscape(x, y-h))/(2*h);
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  1 Comment

Thanks!!!

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