Handle errors in PARI -> CDF conversion

[williamstein]

sage: CDF(pari(1e1000))
sig_error() without sig_on()
------------------------------------------------------------------------
Unhandled SIGABRT: An abort() occurred in Sage.
This probably occurred because a *compiled* component of Sage has a bug
in it and is not properly wrapped with sig_on(), sig_off().
Sage will now terminate.
------------------------------------------------------------------------
./sage: line 134:  7790 Aborted                 "$SAGE_ROOT/src/bin/sage" "$@"

CC: @pjbruin

Component: basic arithmetic

Author: Jeroen Demeyer

Branch/Commit: ff6ddb1

Reviewer: Peter Bruin

Issue created by migration from https://trac.sagemath.org/ticket/17329

[williamstein]

comment:1

This was found by Austin Tran, who reported

f(z)=zeta(z^2)
complex_plot(f,(-10,10),(-10,10),axes=False,figsize=[10,10],plot_points=1000)

which workes fine, but the same expression with zeta(z^3) instead returned the given error. In particular,

f(z)=zeta(z^3)
complex_plot(f,(-10,10),(-10,10),axes=False,figsize=[10,10],plot_points=1000)

gives an error. I tried doing this:

m=0
def f(z):
    global m
    m = z
    return zeta(z^3)

complex_plot(f,(-10,10),(-10,10),axes=False,figsize=[3,3],plot_points=100)

and found that the problem was caused when z = 0.505050505051 - 10.0*I. I then tried explicitly computing zeta(z^3) and got the core dump.

Worksheet: https://cloud.sagemath.com/projects/4a5f0542-5873-4eed-a85c-a18c706e8bcd/files/support/2014-11-12-complex-plot.sagews

[williamstein]

comment:2

Workaround:

def f(z):
    return zeta(CC(z)^3)

complex_plot(f,(-10,10),(-10,10),axes=False,figsize=[3,3],plot_points=100)

[jdemeyer]

Branch: u/jdemeyer/ticket/17329

[jdemeyer]

Author: Jeroen Demeyer

[jdemeyer]

New commits:

ff6ddb1

Handle errors in PARI -> CDF conversion

[jdemeyer]

Commit: ff6ddb1

[pjbruin]

Reviewer: Peter Bruin

[pjbruin]

comment:8

Looks like the right solution to me and passes doctests.

[vbraun]

Changed branch from u/jdemeyer/ticket/17329 to ff6ddb1