How to end function when condition is met
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I havent used Matlab for a while and was never really good at it. I need your help
How to terminate the function, as soon as NL reaches the number 1?
I think i have to put the 'if' and 'return' above the function but then Matlab tells me, that it doesnt know NL yet.
What am I doing wrong?
function NL = NLDestillationsblase(x, x0, Omega1)
NL = (x/x0).^(1./(Omega1-1)).*((1-x0)./(1-x)).^(Omega1./(Omega1-1))
if NL >= 1
return
end
end
4 个评论
Walter Roberson
2020-11-9
编辑：Walter Roberson
2020-11-9
return is fine for this purpose. There is no obvious error in your code... though clearly you would be wanting to loop.
Generally speaking if you are looping, it is cleaner to break the loop and just let the code reach the end of the function instead of returning.
Marcel Langner
2020-11-9
David Hill
2020-11-9
That is because x is an array.
function NL = NLDestillationsblase(x, x0, Omega1)
NL = (x/x0).^(1./(Omega1-1)).*((1-x0)./(1-x)).^(Omega1./(Omega1-1))
NL=NL(NL<1);
end
Marcel Langner
2020-11-9
编辑：Marcel Langner
2020-11-9
采纳的回答
Walter Roberson
2020-11-9
x = 0:0.01:1;
NL = (x/x0).^(1./(Omega1-1)).*((1-x0)./(1-x)).^(Omega1./(Omega1-1))
Because x is a vector, and you are doing element-by-element operations, unless one of the other variables is not a scalar or row vector, then NL would be a row vector. NL is not going to be a scalar, because x is not a scalar and you are not doing any reduction operations such as sum()
if NL >= 1
In MATLAB, when you test a condition using if or while, the condition is considered true if all of the values being tested are non-zero. NL >= 1 with NL non-scalar is going to evaluate to a logical matrix the same sizes as NL. The test would then be considered to be true if all of the NL values are greater than or equal to 1. It is as-if you had written
if all(NL >= 1)
if you want the condition to be true as soon as at least one of the tests is satisfied, then write in any(), as in
if any(NL >= 1)
But you should be considering whether you need to loop over the x values, like
NL = zeros(size(x));
for xidx = 1 : numel(x)
NL(xidx) = (x(xidx)/x0).^(1./(Omega1-1)).*((1-x0)./(1-x(xidx))).^(Omega1./(Omega1-1));
if NL(xidx) >= 1
NL = NL(1:xidx);
return
end
3 个评论
Marcel Langner
2020-11-9
Walter Roberson
2020-11-9
You do not need to pre-allocate, and if you do not do so then you do not need the NL(1:xidx) to trim off extra values.
However, pre-allocating is noticably more efficient to store into.
Marcel Langner
2020-11-9
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