function_derivative_test.cc

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// Copyright (c) 2007, 2008, 2009 libmv authors.
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#include "libmv/numeric/function_derivative.h"
#include "libmv/numeric/numeric.h"
#include "testing/testing.h"
 
using namespace libmv;
 
namespace {
 
class F {
 public:
  typedef Vec2 FMatrixType;
  typedef Vec3 XMatrixType;
  Vec2 operator()(const Vec3& x) const {
    Vec2 fx;
    fx << 0.19 * x(0) + 0.19 * x(1) * x(1) + x(2),
        3 * sin(x(0)) + 2 * cos(x(1));
    return fx;
  }
  Mat23 J(const Vec3& x) const {
    Mat23 jacobian;
    jacobian << 0.19, 2 * 0.19 * x(1), 1.0, 3 * cos(x(0)), -2 * sin(x(1)), 0;
    return jacobian;
  }
};
 
TEST(FunctionDerivative, SimpleCase) {
  Vec3 x;
  x << 0.76026643, 0.01799744, 0.55192142;
  F f;
  NumericJacobian<F, CENTRAL> J(f);
  EXPECT_MATRIX_NEAR(f.J(x), J(x), 1e-8);
  NumericJacobian<F, FORWARD> J_forward(f);
  // Forward difference is very inaccurate.
  EXPECT_MATRIX_NEAR(f.J(x), J_forward(x), 1e-5);
}
 
}  // namespace