RE: strange problem

[THOMAS Paul Richard]

Dear All,

The matrix multiplication gives zero for ans(1,1) in octave 2.1.49 (under
Cygwin)!  However, Matlab5 gives the same result as Gerald's.

Compiling the expression 1-(100*-1)/100 in g++ or intel C++ give 0.  I would
conclude that this is some peculiarity of BLAS that seems to have been
eliminated in later versions of Octave/BLAS.

It seems to me that Gerald's work-around might be to use 

function xout=clean(xin,prec);xout=xin.*(abs(xin)>prec);endfunction; 

so that

a=clean([1,100;0,1]*[1,0;(-1/100),1],1E-16);

a(1,1) yields 0

Paul

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