Moving things..

1 files changed, 118 insertions, 0 deletions

diff --git a/numpy/lib/getlimits.py b/numpy/lib/getlimits.py
new file mode 100644
index 000000000..41030af2d
--- /dev/null
+++ b/numpy/lib/getlimits.py
@@ -0,0 +1,118 @@
+""" Machine limits for Float32 and Float64 and (long double) if available...
+"""
+
+__all__ = ['finfo']
+
+from machar import MachAr
+import numeric
+from numeric import array
+
+def _frz(a):
+    """fix rank-0 --> rank-1"""
+    if a.ndim == 0: a.shape = (1,)
+    return a
+
+_convert_to_float = {
+    numeric.csingle: numeric.single,
+    numeric.complex_: numeric.float_,
+    numeric.clongfloat: numeric.longfloat
+    }
+
+class finfo(object):
+
+    _finfo_cache = {}
+
+    def __new__(cls, dtype):
+        obj = cls._finfo_cache.get(dtype,None)
+        if obj is not None:
+            return obj
+        dtypes = [dtype]
+        newdtype = numeric.obj2dtype(dtype)
+        if newdtype is not dtype:
+            dtypes.append(newdtype)
+            dtype = newdtype
+        if not issubclass(dtype, numeric.inexact):
+            raise ValueError, "data type %r not inexact" % (dtype)
+        obj = cls._finfo_cache.get(dtype,None)
+        if obj is not None:
+            return obj
+        if not issubclass(dtype, numeric.floating):
+            newdtype = _convert_to_float[dtype]
+            if newdtype is not dtype:
+                dtypes.append(newdtype)
+                dtype = newdtype
+        obj = cls._finfo_cache.get(dtype,None)
+        if obj is not None:
+            return obj
+        obj = object.__new__(cls)._init(dtype)
+        for dt in dtypes:
+            cls._finfo_cache[dt] = obj
+        return obj
+
+    def _init(self, dtype):
+        self.dtype = dtype
+        if dtype is numeric.float_:
+            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')
+        elif dtype is numeric.single:
+            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")
+        elif dtype is numeric.longfloat:
+            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")
+        else:
+            raise ValueError,`dtype`
+
+        for word in ['tiny', 'precision', 'resolution','iexp',
+                     'maxexp','minexp','epsneg','negep',
+                     'machep']:
+            setattr(self,word,getattr(machar, word))
+        self.max = machar.huge
+        self.min = -self.max
+        self.eps = machar.epsilon
+        self.nexp = machar.iexp
+        self.nmant = machar.it
+        self.machar = machar
+        self._str_tiny = machar._str_xmin
+        self._str_max = machar._str_xmax
+        self._str_epsneg = machar._str_epsneg
+        self._str_eps = machar._str_eps
+        self._str_resolution = machar._str_resolution
+        return self
+
+    def __str__(self):
+        return '''\
+Machine parameters for %(dtype)s
+---------------------------------------------------------------------
+precision=%(precision)3s   resolution=%(_str_resolution)s
+machep=%(machep)6s   eps=     %(_str_eps)s
+negep =%(negep)6s   epsneg=  %(_str_epsneg)s
+minexp=%(minexp)6s   tiny=    %(_str_tiny)s
+maxexp=%(maxexp)6s   max=     %(_str_max)s
+nexp  =%(nexp)6s   min=       -max
+---------------------------------------------------------------------
+''' % self.__dict__
+
+if __name__ == '__main__':
+    f = finfo(numeric.single)
+    print 'single epsilon:',f.eps
+    print 'single tiny:',f.tiny
+    f = finfo(numeric.float)
+    print 'float epsilon:',f.eps
+    print 'float tiny:',f.tiny
+    f = finfo(numeric.longfloat)
+    print 'longfloat epsilon:',f.eps
+    print 'longfloat tiny:',f.tiny
+