[Numpy-svn] r5151 - in trunk/numpy/ma: . tests

[numpy-svn at scipy.org]

Author: pierregm
Date: 2008-05-09 12:03:36 -0500 (Fri, 09 May 2008)
New Revision: 5151

Modified:
   trunk/numpy/ma/core.py
   trunk/numpy/ma/tests/test_core.py
Log:
core : power : mask all negative values when the exponent (b) doesn't satisfy (abs(b-int(b))<np.finfo(float).precision)

Modified: trunk/numpy/ma/core.py
===================================================================
--- trunk/numpy/ma/core.py	2008-05-09 05:12:31 UTC (rev 5150)
+++ trunk/numpy/ma/core.py	2008-05-09 17:03:36 UTC (rev 5151)
@@ -2842,8 +2842,6 @@
 def power(a, b, third=None):
     """Computes a**b elementwise.
 
-    Masked values are set to 1.
-
     """
     if third is not None:
         raise MAError, "3-argument power not supported."
@@ -2854,14 +2852,16 @@
     fb = getdata(b)
     if fb.dtype.char in typecodes["Integer"]:
         return masked_array(umath.power(fa, fb), m)
-    if numpy.abs(fb) < 1.:
-        md = make_mask((fa < 0), shrink=True)
-        m = mask_or(m, md)
+    md = (abs(fb-int(fb)) < numpy.finfo(float).precision)
+    m = mask_or(m, md) 
     if m is nomask:
         return masked_array(umath.power(fa, fb))
     else:
         fa = fa.copy()
-        fa[m] = 1
+        if m.all():
+            fa[m] = 1
+        else: 
+            numpy.putmask(fa,m,1)
         return masked_array(umath.power(fa, fb), m)
 
 #..............................................................................

Modified: trunk/numpy/ma/tests/test_core.py
===================================================================
--- trunk/numpy/ma/tests/test_core.py	2008-05-09 05:12:31 UTC (rev 5150)
+++ trunk/numpy/ma/tests/test_core.py	2008-05-09 17:03:36 UTC (rev 5151)
@@ -1566,6 +1566,7 @@
         x = -1.1
         assert_almost_equal(power(x,2.), 1.21)
         assert_equal(power(x,0.5)._mask, 1)
+        assert_equal(power(x,masked)._mask, 1)
 
 
 ###############################################################################