This is the working version of the snafu program. Don't peek

jeffsilverm · jeffsilverm · commit a3451c2c4891 · 2013-04-02T20:30:19.000-07:00
diff --git a/week-02/snafu_3.py b/week-02/snafu_3.py
@@ -0,0 +1,49 @@
+#! /usr/bin/env python
+#
+# snafu.py
+# This program is hopelessly screwed up - it is an exercise in using the
+# debugger
+#
+#
+import cmath
+import pdb
+pdb.set_trace()   # for ipython, cpython doesn't need it
+
+def discriminant(A, B, C) :
+    """Return the discriminant of the quadratic: B^2-4AC"""
+    r = cmath.sqrt(B*B - 4*A*C)
+    return r
+
+def abs_err(a, b):
+    return abs(a-b)
+
+def test_function (A, B, C, x, yt, err_limit ) :
+    y = A*x*x+B*x+C
+    assert abs_err(y, yt) <= err_limit,\
+       "The test function returns an incorrect value %f should be %f" % (y.real, yt)
+    return 
+
+#  This is a useless comment
+print "Good values to try include 32,16,0, 1,4,3 and 0,16,32"
+while True:
+    A = float(raw_input("Enter A "))
+    if A != 0.0 :
+        break
+    print "Do not enter the value 0.0 for A"
+    
+B = float(raw_input("Enter B "))
+C = float(raw_input("Enter C "))
+
+d = discriminant(A, B, C)
+    
+
+r1 = (-B + d)/(2*A)
+r2 = (-B - d)/(2*A)
+test_function( A, B, C, r1, 0.0, 1.0E-15 )
+test_function( A, B, C, r2, 0.0, 1.0E-15 )
+                
+
+print "The roots are %s and %s" % ( str(r1), str(r2) )
+
+          
+
