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+#!/usr/bin/env python
+
+#####################
+#! \file floating_point.py
+ ## \verbatim
+ ## Top contributors (to current version):
+ ## Eva Darulova, Makai Mann
+ ## This file is part of the CVC4 project.
+ ## Copyright (c) 2009-2018 by the authors listed in the file AUTHORS
+ ## in the top-level source directory) and their institutional affiliations.
+ ## All rights reserved. See the file COPYING in the top-level source
+ ## directory for licensing information.\endverbatim
+ ##
+ ## \brief A simple demonstration of the solving capabilities of the CVC4
+ ## floating point solver through the Python API contributed by Eva
+ ## Darulova. This requires building CVC4 with symfpu.
+
+import pycvc4
+from pycvc4 import kinds
+
+if __name__ == "__main__":
+ slv = pycvc4.Solver()
+ slv.setOption("produce-models", "true")
+ slv.setLogic("FP")
+
+ # single 32-bit precision
+ fp32 = slv.mkFloatingPointSort(8, 24)
+
+ # the standard rounding mode
+ rm = slv.mkRoundingMode(pycvc4.RoundNearestTiesToEven)
+
+ # create a few single-precision variables
+ x = slv.mkConst(fp32, 'x')
+ y = slv.mkConst(fp32, 'y')
+ z = slv.mkConst(fp32, 'z')
+
+ # check floating-point arithmetic is commutative, i.e. x + y == y + x
+ commutative = slv.mkTerm(kinds.FPEq, slv.mkTerm(kinds.FPPlus, rm, x, y), slv.mkTerm(kinds.FPPlus, rm, y, x))
+
+ slv.push()
+ slv.assertFormula(slv.mkTerm(kinds.Not, commutative))
+ print("Checking floating-point commutativity")
+ print("Expect SAT (property does not hold for NaN and Infinities).")
+ print("CVC4:", slv.checkSat())
+ print("Model for x:", slv.getValue(x))
+ print("Model for y:", slv.getValue(y))
+
+ # disallow NaNs and Infinities
+ slv.assertFormula(slv.mkTerm(kinds.Not, slv.mkTerm(kinds.FPIsNan, x)))
+ slv.assertFormula(slv.mkTerm(kinds.Not, slv.mkTerm(kinds.FPIsInf, x)))
+ slv.assertFormula(slv.mkTerm(kinds.Not, slv.mkTerm(kinds.FPIsNan, y)))
+ slv.assertFormula(slv.mkTerm(kinds.Not, slv.mkTerm(kinds.FPIsInf, y)))
+
+ print("Checking floating-point commutativity assuming x and y are not NaN or Infinity")
+ print("Expect UNSAT.")
+ print("CVC4:", slv.checkSat())
+
+ # check floating-point arithmetic is not associative
+ slv.pop()
+
+ # constrain x, y, z between -3.14 and 3.14 (also disallows NaN and infinity)
+ a = slv.mkFloatingPoint(8, 24, slv.mkBitVector("11000000010010001111010111000011", 2)) # -3.14
+ b = slv.mkFloatingPoint(8, 24, slv.mkBitVector("01000000010010001111010111000011", 2)) # 3.14
+
+ bounds_x = slv.mkTerm(kinds.And, slv.mkTerm(kinds.FPLeq, a, x), slv.mkTerm(kinds.FPLeq, x, b))
+ bounds_y = slv.mkTerm(kinds.And, slv.mkTerm(kinds.FPLeq, a, y), slv.mkTerm(kinds.FPLeq, y, b))
+ bounds_z = slv.mkTerm(kinds.And, slv.mkTerm(kinds.FPLeq, a, z), slv.mkTerm(kinds.FPLeq, z, b))
+ slv.assertFormula(slv.mkTerm(kinds.And, slv.mkTerm(kinds.And, bounds_x, bounds_y), bounds_z))
+
+ # (x + y) + z == x + (y + z)
+ lhs = slv.mkTerm(kinds.FPPlus, rm, slv.mkTerm(kinds.FPPlus, rm, x, y), z)
+ rhs = slv.mkTerm(kinds.FPPlus, rm, x, slv.mkTerm(kinds.FPPlus, rm, y, z))
+ associative = slv.mkTerm(kinds.Not, slv.mkTerm(kinds.FPEq, lhs, rhs))
+
+ slv.assertFormula(associative)
+
+ print("Checking floating-point associativity")
+ print("Expect SAT.")
+ print("CVC4:", slv.checkSat())
+ print("Model for x:", slv.getValue(x))
+ print("Model for y:", slv.getValue(y))
+ print("Model for z:", slv.getValue(z))
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