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Re: PDL::Complex question

by Zaxo (Archbishop)
on Mar 22, 2007 at 06:53 UTC ( [id://605967]=note: print w/replies, xml ) Need Help??


in reply to PDL::Complex question

Column vectors should be piddled as,

my $matrixB_assigned_value = pdl [ [5+8*i], [10-5*i] ]; my $matrixX_assigned_value = pdl [ [3+1*i], [2+1*i ] ];
Untested, but I think that will give you the results you expect.

After Compline,
Zaxo

Replies are listed 'Best First'.
Re^2: PDL::Complex question
by Anno (Deacon) on Mar 22, 2007 at 13:53 UTC
    One should think so, but it doesn't.

    Conventional notation would have the 2x2 matrix left, the column vector to the right, so

    print " result: ", $matrixM x $matrixX_assigned_value;
    but that complains
    PDL: Dim mismatch in matmult of [2x2] x [2x1]: 2 != 1
    Swapping the factors
    print "should be: ", $matrixB_assigned_value; print " result: ", $matrixX_assigned_value x $matrixM;
    prints
    should be: [ [ [5 8] ] [ [10 -5] ] ] result: [ [ [5 4] ] [ [ 4 -5] ] ]
    The result looks like a column vector, but is numerically incorrect.

    BTW, it helps to cast the piddles into the PDL::Complex data type, using the cplx function. That overloads stringification so that the complex elements are printed in a x + i*y format instead of looking like pairs of reals. The numeric discrepancy remains, however.

    Anno

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