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Incorrect finfo from PPC longdouble (Trac #2077) #2669

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Original ticket http://projects.scipy.org/numpy/ticket/2077 on 2012-03-10 by @matthew-brett, assigned to unknown.

In [1]: import numpy as np

In [2]: print np.finfo(np.longdouble)
/Users/mb312/dev_trees/numpy/numpy/core/machar.py:125: RuntimeWarning: overflow encountered in add
  a = a + a
/Users/mb312/dev_trees/numpy/numpy/core/machar.py:127: RuntimeWarning: invalid value encountered in subtract
  temp1 = temp - a
/Users/mb312/dev_trees/numpy/numpy/core/machar.py:136: RuntimeWarning: invalid value encountered in subtract
  itemp = int_conv(temp-a)
/Users/mb312/dev_trees/numpy/numpy/core/machar.py:160: RuntimeWarning: overflow encountered in add
  a = a + a
/Users/mb312/dev_trees/numpy/numpy/core/machar.py:162: RuntimeWarning: invalid value encountered in subtract
  temp1 = temp - a
/Users/mb312/dev_trees/numpy/numpy/core/machar.py:169: RuntimeWarning: invalid value encountered in subtract
  if any(temp-a != zero):
Machine parameters for float128
---------------------------------------------------------------------
precision= 75   resolution= 1e-75
machep=    -4   eps=        1.3817869701e-76
negep =    -4   epsneg=     1.3817869701e-76
minexp=    -1   tiny=       -1.08420217274e-19
maxexp=     1   max=        -9.22337203471e+18
nexp  =     1   min=        -max
---------------------------------------------------------------------


In [3]: print np.finfo(np.longdouble).nmant
1

In [4]: np.__version__
Out[4]: '1.7.0.dev-aae5b0a'

I think the correct answers for nexp, nmant are 11, 106 respectively; see:
https://developer.apple.com/library/mac/#documentation/Darwin/Reference/Manpages/man3/float.3.html

(np-devel)[mb312@jerry ~]$ uname -a
Darwin jerry.bic.berkeley.edu 8.11.0 Darwin Kernel Version 8.11.0: Wed Oct 10 18:26:00 PDT 2007; root:xnu-792.24.17~1/RELEASE_PPC Power Macintosh powerpc
(np-devel)[mb312@jerry ~]$ gcc -v
Using built-in specs.
Target: powerpc-apple-darwin8
Configured with: /var/tmp/gcc/gcc-5370~2/src/configure --disable-checking -enable-werror --prefix=/usr --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-transform-name=/^[cg][^.-]*$/s/$/-4.0/ --with-gxx-include-dir=/include/c++/4.0.0 --with-slibdir=/usr/lib --build=powerpc-apple-darwin8 --host=powerpc-apple-darwin8 --target=powerpc-apple-darwin8
Thread model: posix
gcc version 4.0.1 (Apple Computer, Inc. build 5370)

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