[Maxima] Test suite failures with cvs version?
raymond.toy at ericsson.com
Mon Oct 27 08:43:53 CDT 2008
Dieter Kaiser wrote:
> (defun expintegral-ei (z)
> (- (expintegral-e 1 (- z)))
> ; (- (* 0.5 (- (log z) (log (/ 1 z)))) (log (- z)))
> (if (and (= (imagpart z) 0) (> (realpart z) 0))
> ;; Positive real value. Add a phase factor -%pi*%i
> (complex 0 (- (float pi)))
> ;; For all other values. No phase factor.
I was getting ready to check in all the changes we had done last week,
but I was looking at this expression. I must be stupid. I don't see
how f(z) = 1/2*(log(z)-log(1/z)) - log(-z) simplifies that way. For
real z, yes, I see f(z) is -%i*%pi for positive z and 0 for negative z.
But for complex z, not on the real axis, I always get %i*%pi (or
-%i*%pi, depending on how you want to write -1).
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