CODEWITHSUNDEEP
matlabif-statementlogical-operators
clarkson
clarkson

Reputation: 571

& in if else condition in matlab

I want to write a function in Matlab for
enter image description here

This is what I wrote. 

function f=hamacher(x,y)
for i=1:5
    if x==0.00 & y==0.00
        f=0;
    else 
        f=(x.*y)./(x+y-(x.*y));
    end
end
end

If I let 

>> p=[0 0.5 1 0 0.75];
>> q=[0 0.2 0 0 0.8];
>> hamacher(p,q)

ans =

       NaN    0.1667         0       NaN    0.6316

This results NaN and not 0 because of 0/0. I want to handle this issue by
if x==0.00 & y==0.00 f=0;

Why doesn't this if statement handle this?
Can someone please tell me how I can correct this.

Upvotes: 1

Views: 136

Answers (2)

Luis Mendo
Luis Mendo

Reputation: 112769

Since your function is vectorized, use logical indexing to distinguish the two cases element-wise:

ind = x==0 & y==0;
f(ind) = 0;
f(~ind) = x(~ind).*y(~ind)./(x(~ind)+y(~ind)-(x(~ind).*y(~ind)));

Upvotes: 3

Adriaan
Adriaan

Reputation: 18197

function f=hamacher(x,y)
f = zeros(numel(x),1);
for ii=1:numel(x)
    if x(ii)==0 && y(ii)==0
        f(ii,1)=0;
    else 
        f(ii,1)=(x(ii)*y(ii))/(x(ii)+y(ii)-(x(ii)*y(ii)));
    end
end
end
>> p=[0 0.5 1 0 0.75];
>> q=[0 0.2 0 0 0.8];
>> hamacher(p,q)
ans = 

         0
    0.1667
         0
         0
    0.6316

I'm quite sure this is what you wanted. I just made sure everything works element wise and not vectorised.

Upvotes: 1

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