distance_test.cpp

#include <stan/math/fwd/scal.hpp>
#include <gtest/gtest.h>

TEST(Fwd, distance) {
    using stan::math::fvar;
    using stan::math::distance;

    fvar<double> x1(1.0,1.0);
    fvar<double> x2(4.0,1.0);

    double x1c = 1.0;
    double x2c = 4.0;

    fvar<double> dx1 = distance(x1,x2c);
    EXPECT_FLOAT_EQ(3, dx1.val_);
    EXPECT_FLOAT_EQ(-1,dx1.d_);

    fvar<double> dx2 = distance(x1c,x2);
    EXPECT_FLOAT_EQ(3, dx2.val_);
    EXPECT_FLOAT_EQ(1,dx2.d_);

    dx1= distance(x1,x1c);
    EXPECT_FLOAT_EQ(0,dx1.val_);
    EXPECT_TRUE(stan::math::is_nan(dx1.d_));

    dx1= distance(x1c,x1);
    EXPECT_FLOAT_EQ(0,dx1.val_);
    EXPECT_TRUE(stan::math::is_nan(dx1.d_));


}

TEST(Fwd, distance_nan) {
  using stan::math::fvar;
  using stan::math::distance;
  double x1 = 1;
  double nan = std::numeric_limits<double>::quiet_NaN();

  fvar<double> x2(nan,1.0);

  EXPECT_THROW(distance(x1, x2), std::domain_error);
  EXPECT_THROW(distance(x2, x1), std::domain_error);
  EXPECT_THROW(distance(x2, x2), std::domain_error);

}

TEST(Fwd, distance_inf) {
  using stan::math::fvar;
  using stan::math::distance;
  double x1 = 1;
  double inf = std::numeric_limits<double>::infinity();

  fvar<double> x2(inf,1.0);

  EXPECT_THROW(distance(x1, x2), std::domain_error);
  EXPECT_THROW(distance(x2, x1), std::domain_error);
  EXPECT_THROW(distance(x2, x2), std::domain_error);
}