Changeset 3849

Timestamp:

Oct 24, 2006, 4:14:51 PM (19 years ago)

Author:

ole

Message:

Added function and test for calculating machine precision for Python Floats

Location:

anuga_core/source/anuga/utilities

Files:

• numerical_tools.py (modified) (1 diff)
• test_numerical_tools.py (modified) (1 diff)

anuga_core/source/anuga/utilities/numerical_tools.py

@@ -288 +288 @@
     return bins
 
-
+def get_machine_precision():
+    """Calculate the machine precision for Floats
+    """
+
+    epsilon = 1.
+    while epsilon/2 + 1. > 1.:
+        epsilon /= 2
+
+    return epsilon    
 
 ####################################################################

anuga_core/source/anuga/utilities/test_numerical_tools.py

@@ -186 +186 @@
 
 
+    def test_machine_precision(self):
+        """test_machine_precision(self):
+        Test the function that calculates epsilon. As this varies on
+        different machines, this is only an indication.
+        """
+
+        eps = get_machine_precision()
+
+        assert eps < 1.0e-12, 'Machine precision should be better than 1.0e-12'
+        assert eps > 0.0
+        assert 1.0+eps/2 == 1.0
+        
+        
     def test_histogram(self):
         """Test histogram with different bin boundaries