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""" Machine limits for Float32 and Float64 and (long double) if available...
"""
__all__ = ['finfo']
import sys
from machar import MachAr
import numeric
from numeric import array
def frz(a):
"""fix rank-0 --> rank-1"""
if len(a.shape) == 0:
a = a.reshape((1,))
return a
_convert_to_float = {
numeric.csingle: numeric.single,
numeric.acomplex: numeric.afloat,
numeric.clongfloat: numeric.longfloat
}
_machar_cache = {}
class finfo(object):
def __init__(self, dtype):
dtype = numeric.obj2dtype(dtype)
if not issubclass(dtype, numeric.inexact):
raise ValueError, "data type not inexact"
if not issubclass(dtype, numeric.floating):
dtype = _convert_to_float[dtype]
if dtype is numeric.afloat:
try:
self.machar = _machar_cache[numeric.afloat]
except KeyError:
self.machar = MachAr(lambda v:array([v],'d'),
lambda v:frz(v.astype('i'))[0],
lambda v:array(frz(v)[0],'d'),
lambda v:'%24.16e' % array(frz(v)[0],'d'),
'scipy float precision floating point '\
'number')
_machar_cache[numeric.afloat] = self.machar
elif dtype is numeric.single:
try:
self.machar = _machar_cache[numeric.single]
except KeyError:
self.machar = MachAr(lambda v:array([v],'f'),
lambda v:frz(v.astype('i'))[0],
lambda v:array(frz(v)[0],'f'), #
lambda v:'%15.7e' % array(frz(v)[0],'f'),
"scipy single precision floating "\
"point number")
_machar_cache[numeric.single] = self.machar
elif dtype is numeric.longfloat:
try:
self.machar = _machar_cache[numeric.longfloat]
except KeyError:
self.machar = MachAr(lambda v:array([v],'g'),
lambda v:frz(v.astype('i'))[0],
lambda v:array(frz(v)[0],'g'), #
lambda v:str(array(frz(v)[0],'g')),
"scipy longfloat precision floating "\
"point number")
_machar_cache[numeric.longfloat] = self.machar
for word in ['tiny', 'precision', 'resolution',
'ngrd','maxexp','minexp','epsneg','negep',
'machep']:
setattr(self,word,getattr(self.machar, word))
self.max = self.machar.huge
self.min = -self.max
self.eps = self.machar.epsilon
self.nexp = self.machar.iexp
self.nmant = self.machar.it
if __name__ == '__main__':
f = finfo(numeric.single)
print 'single epsilon:',f.epsilon
print 'single tiny:',f.tiny
f = finfo(numeric.float)
print 'float epsilon:',f.epsilon
print 'float tiny:',f.tiney
f = finfo(numeric.longfloat)
print 'longfloat epsilon:',f.epsilon
print 'longfloat tiny:',f.tiny
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