#1891: Problems with acosh, asech, atanh and acoth in Complex PMC
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Reporter: fbrito | Owner: Util
Type: bug | Status: assigned
Priority: normal | Milestone: 2.11
Component: core | Version: 2.10.0
Severity: medium | Keywords: complex math trig
Lang: | Patch:
Platform: all |
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Changes (by Util):
* status: new => assigned
Comment:
Be advised, problems are turning up in other data sources:
I will rely on the standard C library as the "absolute truth", until
counter-evidence arrives.
{{{
#include <stdio.h>
#include <complex.h>
int main(void) {
const double complex z = 2.0 - 3.0 * I;
const double complex c = cacosh(z);
printf(
"cacosh(%lg%+lgi) is %lf%+lfi\n",
creal(z), cimag(z),
creal(c), cimag(c)
);
return 0;
}
}}}
Outputs:
cacosh(2-3i) is 1.983387-1.000144i
http://www.wolframalpha.com/input/?i=acosh(2-3i)
1.983387-1.00014354247i
More evidence that the C answer is correct.
perl -MMath::Complex -wle '$f=cplxe(2,-3); $g = acosh $f;
print "$g"'
1.32074266859523-2.97863118461102i
Looks completely wrong to me. Also, when fed back into cosh(),
does not even come close to (2,-3).
perl -MMath::Cephes::Complex=cmplx -wle '$f=cmplx(2,-3); $g = $f->cacosh;
print $g->as_string'
-1.983387 + 1.000144 i
The signs are backwards, but cosh(z) == cosh(-z), so maybe this is
just another form of "correct"?
Will pursue further tomorrow.
--
Ticket URL: <https://trac.parrot.org/parrot/ticket/1891#comment:2>
Parrot <https://trac.parrot.org/parrot/>
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