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diff --git a/intern/libmv/libmv/numeric/poly_test.cc b/intern/libmv/libmv/numeric/poly_test.cc
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+++ b/intern/libmv/libmv/numeric/poly_test.cc
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+// Copyright (c) 2007, 2008 libmv authors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+
+#include "libmv/numeric/numeric.h"
+#include "libmv/numeric/poly.h"
+#include "testing/testing.h"
+
+using namespace libmv;
+
+namespace {
+
+// Find the polynomial coefficients of x in the equation
+//
+//   (x - a)(x - b)(x - c) == 0
+//
+// by expanding to
+//
+//   x^3 - (c+b+a) * x^2 + (a*b+(b+a)*c) * x - a*b*c = 0.
+//           = p               = q              = r
+void CoeffsForCubicZeros(double a, double b, double c,
+                    double *p, double *q, double *r) {
+  *p = -(c + b + a);
+  *q = (a * b + (b + a) * c);
+  *r = -a * b * c;
+}
+
+TEST(Poly, SolveCubicPolynomial) {
+  double a, b, c, aa, bb, cc;
+  double p, q, r;
+
+  a = 1; b = 2; c = 3;
+  CoeffsForCubicZeros(a, b, c, &p, &q, &r);
+  ASSERT_EQ(3, SolveCubicPolynomial(p, q, r, &aa, &bb, &cc));
+  EXPECT_NEAR(a, aa, 1e-10);
+  EXPECT_NEAR(b, bb, 1e-10);
+  EXPECT_NEAR(c, cc, 1e-10);
+
+  a = 0; b = 1; c = 3;
+  CoeffsForCubicZeros(a, b, c, &p, &q, &r);
+  ASSERT_EQ(3, SolveCubicPolynomial(p, q, r, &aa, &bb, &cc));
+  EXPECT_NEAR(a, aa, 1e-10);
+  EXPECT_NEAR(b, bb, 1e-10);
+  EXPECT_NEAR(c, cc, 1e-10);
+
+  a = -10; b = 0; c = 1;
+  CoeffsForCubicZeros(a, b, c, &p, &q, &r);
+  ASSERT_EQ(3, SolveCubicPolynomial(p, q, r, &aa, &bb, &cc));
+  EXPECT_NEAR(a, aa, 1e-10);
+  EXPECT_NEAR(b, bb, 1e-10);
+  EXPECT_NEAR(c, cc, 1e-10);
+
+  a = -8; b = 1; c = 3;
+  CoeffsForCubicZeros(a, b, c, &p, &q, &r);
+  ASSERT_EQ(3, SolveCubicPolynomial(p, q, r, &aa, &bb, &cc));
+  EXPECT_NEAR(a, aa, 1e-10);
+  EXPECT_NEAR(b, bb, 1e-10);
+  EXPECT_NEAR(c, cc, 1e-10);
+
+  a = 28; b = 28; c = 105;
+  CoeffsForCubicZeros(a, b, c, &p, &q, &r);
+  ASSERT_EQ(3, SolveCubicPolynomial(p, q, r, &aa, &bb, &cc));
+  EXPECT_NEAR(a, aa, 1e-10);
+  EXPECT_NEAR(b, bb, 1e-10);
+  EXPECT_NEAR(c, cc, 1e-10);
+}
+}  // namespace