----maxima-bounces at math.utexas.edu wrote: -----
>(%i1) load("linearalgebra");
>(%i2) B: matrix([3,4],[4,5]);
>(%i3) mat_cond(B,1); --> 84
>(%i4) mat_cond(B,inf); --> 84
>
>which should be 24.
Why 24? I get(with Maxima 5.11.0
(%i1) load(linearalgebra)$
(%i2) B: matrix([3,4],[4,5])$
(%i3) mat_cond(B,1);
(%o3) 81
(%i4) mat_cond(B, 'inf);
(%o4) 81
I'm perplexed that you got 84 with Maxima 5.11.0. I also
don't know why you expected 24 for the infinity norm.
>I was surprised and calculated the matrix norm (which was also 'wrong')
What did you get? What did you expect?
(%i5) mat_norm(B,1);
(%o5) 9
(%i6) mat_norm(B,'inf);
(%o6) 9
Aren't these OK? row sum = 9 and column sum = 9.
>and also
>
>(%i5) B^^-1; --> [ 5 -3]
> [-4 3]
>
>which I expected to be 1/3* above.
Why did you expect an additional factor of 1/3? I get
(%i9) B^^-1;
(%o9) matrix([-5,4],[4,-3])
(%i10) %.B;
(%o10) matrix([1,0],[0,1])
Also the row and column sums of B^^-1 are 9. So the condition
number is 81 for both the 1 and infinity norms.
Barton