[Lib2geom-devel] size comparison in Affine::inverse()

[Alvin P. <pe...@va...>]

while investigating LP Bug 1231990, 
https://bugs.launchpad.net/inkscape/+bug/1231990, it was found that 
the routine Affine::inverse() in the file affine.cpp is apparently 
refusing to calculate the inverse of the following matrix:

0.001,    0.0
0.0,    150.0

The refusal is coming from the line:
if (!rel_error_bound(determ, mx*mx))

I would like to propose that this be changed to:
if (!rel_error_bound(std::sqrt(fabs(determ)), mx))
so that we would be comparing two numbers which both have units of 
length. This would be similar to a change was made in rev 2183, where 
a similar size comparison problem was encountered (LP Bug 1309225).

Any comments?

Cheers,
Alvin