from_str: wrong parsing with underscores after decimal #377
Description
This works:
>>> mpmath.libmp.from_str('1_234.567891', 80)
(0, mpz(91095031707585398740483), -66, 77)
>>> mpmath.libmp.to_str(_, 24)
'1234.567891'
But underscores placed after the decimal point shift the decimal point incorrectly:
>>> mpmath.libmp.from_str('1_234.567_891', 80)
(0, mpz(1166016405857093103878183), -73, 80)
>>> mpmath.libmp.to_str(_, 24)
'123.4567891'
>>> mpmath.libmp.from_str('1_234.567_8_9_1', 80)
(0, mpz(746250499748539586482037), -79, 80)
>>> mpmath.libmp.to_str(_, 24)
'1.234567891'
The docs say "The literal syntax accepted is the same as for Python floats". But this is not so:
>>> 1_234.567_8_9_1
1234.567891