Why does Matlab incorrectly return 0 when evaluating an array, but correctly return NaN when evaluating a scalar? -

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why expression h(theta) below return 0 , return nan? h(theta) contains division 0 theta = 0 , should return nan. if ask h(0), works fine.

however, when evaluates 0 contained in multi-element array, returns h = 0 when should return nan. if evaluating element zero, returns nan should.

>> theta = [0 1] theta =      0     1

the first element should nan:

>> h = tan(theta)/(1+(tan(theta)/tan(2.*theta))) h =      0    5.4220

when evaluating 0 element works correctly:

>> h = tan(theta(1))/(1+(tan(theta(1))/tan(2.*theta(1)))) h =      nan   >> h = tan(theta(2))/(1+(tan(theta(2))/tan(2.*theta(2)))) h =      5.4220

you need element-wise division ./ instead of / desired result. called right array division.

>> h = tan(theta)./(1+(tan(theta)./tan(2.*theta))) h =        nan    5.4220

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