Re: Complex matrix multiplication fails

[Judd Storrs]

On Wed, May 12, 2010 at 8:21 AM, Børge Strand-Bergesen
<address@hidden> wrote:
> Do you see any errors in my code? Are there any known bugs here?
> Curiously, if I replace
> CEM=WN.^CEM; by CEM=WM.^-CEM; the complex matrix multiplication
> matches fft() but the matrix
> applied manually does not.

I suspect you're seeing the matlab/octave complex conjugate trap. In
matlab/octave x' takes the complex conjugate. If you just want to flip
the matrix you need to use .'

octave:1> a = 1+i
a =  1 + 1i
octave:2> a'
ans =  1 - 1i
octave:3> a.'
ans =  1 + 1i

Flipping the sign of the exponent "fixes" the problem by double negation.

octave:4> exp(i)
ans =  0.54030 + 0.84147i
octave:5> exp(-i)'
ans =  0.54030 + 0.84147i

Again, apologies if I've misunderstood the problem.


--judd