exposed subresultants aka psc-chain procedure

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/api/python/z3poly.py

@@ -0,0 +1,37 @@
+############################################
+# Copyright (c) 2012 Microsoft Corporation
+# 
+# Z3 Python interface for Z3 polynomials
+#
+# Author: Leonardo de Moura (leonardo)
+############################################
+from z3 import *
+
+def subresultants(p, q, x):
+    """
+    Return the non-constant subresultants of 'p' and 'q' with respect to the "variable" 'x'.
+
+    'p', 'q' and 'x' are Z3 expressions where 'p' and 'q' are arithmetic terms.
+    Note that, any subterm that cannot be viewed as a polynomial is assumed to be a variable.
+    Example: f(a) is a considered to be a variable b in the polynomial       
+
+    f(a)*f(a) + 2*f(a) + 1 
+    
+    >>> x, y = Reals('x y')
+    >>> subresultants(2*x + y, 3*x - 2*y + 2, x)
+    [-7*y + 4]
+    >>> r = subresultants(3*y*x**2 + y**3 + 1, 2*x**3 + y + 3, x)
+    >>> r[0]
+    4*y**9 + 12*y**6 + 27*y**5 + 162*y**4 + 255*y**3 + 4
+    >>> r[1]
+    -6*y**4 + -6*y
+    """
+    return AstVector(Z3_polynomial_subresultants(p.ctx_ref(), p.as_ast(), q.as_ast(), x.as_ast()), p.ctx)
+
+if __name__ == "__main__":
+    import doctest
+    if doctest.testmod().failed:
+        exit(1)
+
+
+