""" 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.complex_: numeric.float_,
    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.float_:
            try:
                self.machar = _machar_cache[numeric.float_]
            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.float_] = 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