[fixed, awaits confirmation] plot3d/transform.pyx test failure

[garyfurnish]

Failure on make check

sage -t  devel/sage-main/sage/plot/plot3d/transform.pyx     �[?1034h**********************************************************************
File "transform.pyx", line 213:
    sage: m
Expected:
    [                                                                                                                                        (x^2*z^2 - (cos(theta)*x^2 - cos(theta))*z^2)/z^2                                                                                                          (-sqrt(-z^2 - x^2 + 1)*(cos(theta)*x*abs(z) - x*abs(z)) - sin(theta)*z^2)/abs(z)                                                                                                (-cos(theta)*x*z^2*abs(z) + x*z^2*abs(z) + sin(theta)*z^2*sqrt(-z^2 - x^2 + 1))/(z*abs(z))]
    [                                                                                                            (sin(theta)*z^2*abs(z) - sqrt(-z^2 - x^2 + 1)*(cos(theta)*x*z^2 - x*z^2))/z^2                                              ((-(x^2 + cos(theta) - 1)*z^2 - x^4 + 2*x^2 - 1)*abs(z) - (-cos(theta)*x^2*z^2 - cos(theta)*x^4 + cos(theta)*x^2)*abs(z))/((x^2 - 1)*abs(z)) (-sqrt(-z^2 - x^2 + 1)*(cos(theta)*x^2*z^2*abs(z) + (-x^2 - cos(theta) + 1)*z^2*abs(z)) + sin(theta)*x*z^4 - z^2*(sin(theta)*x*z^2 + sin(theta)*x^3 - sin(theta)*x))/((x^2 - 1)*z*abs(z))]
    [                                                                                                               (-sin(theta)*z*sqrt(-z^2 - x^2 + 1)*abs(z) - cos(theta)*x*z^3 + x*z^3)/z^2                                               (-sqrt(-z^2 - x^2 + 1)*(cos(theta)*x^2*z*abs(z) + (-x^2 - cos(theta) + 1)*z*abs(z)) - (sin(theta)*x - sin(theta)*x^3)*z)/((x^2 - 1)*abs(z))                                                                        (((x^2 + cos(theta) - 1)*z^2 + cos(theta)*x^2 - cos(theta))*abs(z) - cos(theta)*x^2*z^2*abs(z))/((x^2 - 1)*abs(z))]
Got:
    [                                                                                                                                                                                                              sage17*cos(theta)*sqrt(1 - x^2) + sage13*sage76                                                                                                                                                                               (sqrt(-z^2 - x^2 + 1)*(sage76*abs(z) - cos(theta)*x*z) - sin(theta)*z*abs(z))/z                                                                                                                                                                               (sin(theta)*sqrt(-z^2 - x^2 + 1)*abs(z) + sage76*z*abs(z) - cos(theta)*x*z^2)/z]
    [                                                                                                                 (sqrt(1 - x^2)*sqrt(-z^2 - x^2 + 1)*(sage17*cos(theta)*x*abs(z) + sage13*sage80*z) - sage17*sin(theta)*sqrt(1 - x^2)*z^2)/((x^2 - 1)*abs(z))                                          (-sqrt(1 - x^2)*((-cos(theta)*x^2*z^2 - cos(theta)*x^4 + cos(theta)*x^2)*abs(z) + cos(theta)*z^2*abs(z)) - ((sage80 - sage80*x^2)*z^2 - sage80*x^4 + 2*sage80*x^2 - sage80)*abs(z))/(sqrt(1 - x^2)*(x^2 - 1)*abs(z)) (-sqrt(-z^2 - x^2 + 1)*(sqrt(1 - x^2)*(cos(theta)*x^2*z^2*abs(z) - cos(theta)*z^2*abs(z)) + (sage80*x^2 - sage80)*z^2*abs(z)) - sqrt(1 - x^2)*(z^2*(sin(theta)*x*z^2 + sin(theta)*x^3 - sin(theta)*x) - sin(theta)*x*z^4))/(sqrt(1 - x^2)*(x^2 - 1)*z*abs(z))]
    [                                                                                                               (sqrt(1 - x^2)*(sage17*cos(theta)*x*z*abs(z) + sage13*sage80*z^2) + sage17*sin(theta)*sqrt(1 - x^2)*z*sqrt(-z^2 - x^2 + 1))/((x^2 - 1)*abs(z))                                                   (-sqrt(-z^2 - x^2 + 1)*(sqrt(1 - x^2)*(cos(theta)*x^2*z*abs(z) - cos(theta)*z*abs(z)) + (sage80*x^2 - sage80)*z*abs(z)) - sqrt(1 - x^2)*(sin(theta)*x - sin(theta)*x^3)*z)/(sqrt(1 - x^2)*(x^2 - 1)*abs(z))                                                                                       (sqrt(1 - x^2)*((cos(theta)*z^2 + cos(theta)*x^2 - cos(theta))*abs(z) - cos(theta)*x^2*z^2*abs(z)) + (sage80 - sage80*x^2)*z^2*abs(z))/(sqrt(1 - x^2)*(x^2 - 1)*abs(z))]
**********************************************************************

System is 64 bit gentoo, gcc 4.2.2

Component: doctest coverage

Issue created by migration from https://trac.sagemath.org/ticket/1827

[williamstein]

Attachment: trac-1827.patch.gz

this should completely fix the problem. But I've only tested it on one 32-bit linux system. it needs more testing

[robertwb]

comment:3

For _an_element_impl, it should return a very generic element. If it returns zero, then it may mess up the coercion model!

[sagetrac-mabshoff]

comment:4

Hi Robert,

can you provide a doctest that exposes the issue you describe?

Cheers,

Michael

[robertwb]

comment:6

OK, I take this back.

It used to be that some multiplication code was written as

def _lmul_(self, other):
    if not other:
        return other
    ...

This would succeed when other was ANY type with bool(other) == False, and an_element was used to construct other to pass in and try it out (in the action detection code) which would cause it to succeed and this "valid" action would get cached (resulting in a error or segfault when a non-zero other was passed.

It now forces other to be an element of self.parent().base_ring(), which solves this problem.