from __future__ import division, print_function, absolute_import

import numpy as np
from numpy import cos, sin, pi
from numpy.testing import TestCase, run_module_suite, assert_equal, \
    assert_almost_equal, assert_allclose

from scipy.integrate import quadrature, romberg, romb, newton_cotes, cumtrapz


class TestQuadrature(TestCase):
    def quad(self, x, a, b, args):
        raise NotImplementedError

    def test_quadrature(self):
        # Typical function with two extra arguments:
        def myfunc(x,n,z):       # Bessel function integrand
            return cos(n*x-z*sin(x))/pi
        val, err = quadrature(myfunc,0,pi,(2,1.8))
        table_val = 0.30614353532540296487
        assert_almost_equal(val, table_val, decimal=7)

    def test_quadrature_rtol(self):
        def myfunc(x,n,z):       # Bessel function integrand
            return 1e90 * cos(n*x-z*sin(x))/pi
        val, err = quadrature(myfunc,0,pi,(2,1.8),rtol=1e-10)
        table_val = 1e90 * 0.30614353532540296487
        assert_allclose(val, table_val, rtol=1e-10)

    def test_romberg(self):
        # Typical function with two extra arguments:
        def myfunc(x, n, z):       # Bessel function integrand
            return cos(n*x-z*sin(x))/pi
        val = romberg(myfunc,0,pi, args=(2, 1.8))
        table_val = 0.30614353532540296487
        assert_almost_equal(val, table_val, decimal=7)

    def test_romberg_rtol(self):
        # Typical function with two extra arguments:
        def myfunc(x, n, z):       # Bessel function integrand
            return 1e19*cos(n*x-z*sin(x))/pi
        val = romberg(myfunc,0,pi, args=(2, 1.8), rtol=1e-10)
        table_val = 1e19*0.30614353532540296487
        assert_allclose(val, table_val, rtol=1e-10)

    def test_romb(self):
        assert_equal(romb(np.arange(17)),128)

    def test_non_dtype(self):
        # Check that we work fine with functions returning float
        import math
        valmath = romberg(math.sin, 0, 1)
        expected_val = 0.45969769413185085
        assert_almost_equal(valmath, expected_val, decimal=7)

    def test_newton_cotes(self):
        """Test the first few degrees, for evenly spaced points."""
        n = 1
        wts, errcoff = newton_cotes(n, 1)
        assert_equal(wts, n*np.array([0.5, 0.5]))
        assert_almost_equal(errcoff, -n**3/12.0)

        n = 2
        wts, errcoff = newton_cotes(n, 1)
        assert_almost_equal(wts, n*np.array([1.0, 4.0, 1.0])/6.0)
        assert_almost_equal(errcoff, -n**5/2880.0)

        n = 3
        wts, errcoff = newton_cotes(n, 1)
        assert_almost_equal(wts, n*np.array([1.0, 3.0, 3.0, 1.0])/8.0)
        assert_almost_equal(errcoff, -n**5/6480.0)

        n = 4
        wts, errcoff = newton_cotes(n, 1)
        assert_almost_equal(wts, n*np.array([7.0, 32.0, 12.0, 32.0, 7.0])/90.0)
        assert_almost_equal(errcoff, -n**7/1935360.0)

    def test_newton_cotes2(self):
        """Test newton_cotes with points that are not evenly spaced."""

        x = np.array([0.0, 1.5, 2.0])
        y = x**2
        wts, errcoff = newton_cotes(x)
        exact_integral = 8.0/3
        numeric_integral = np.dot(wts, y)
        assert_almost_equal(numeric_integral, exact_integral)

        x = np.array([0.0, 1.4, 2.1, 3.0])
        y = x**2
        wts, errcoff = newton_cotes(x)
        exact_integral = 9.0
        numeric_integral = np.dot(wts, y)
        assert_almost_equal(numeric_integral, exact_integral)


class TestCumtrapz(TestCase):
    def test_1d(self):
        x = np.linspace(-2, 2, num=5)
        y = x
        y_int = cumtrapz(y, x, initial=0)
        y_expected = [0., -1.5, -2., -1.5, 0.]
        assert_allclose(y_int, y_expected)

        y_int = cumtrapz(y, x, initial=None)
        assert_allclose(y_int, y_expected[1:])

    def test_nd(self):
        x = np.arange(3 * 2 * 4).reshape(3, 2, 4)
        y = x
        y_int = cumtrapz(y, x, initial=0)
        y_expected = np.array([[[  0. ,   0.5,   2. ,   4.5],
                                [  0. ,   4.5,  10. ,  16.5]],
                               [[  0. ,   8.5,  18. ,  28.5],
                                [  0. ,  12.5,  26. ,  40.5]],
                               [[  0. ,  16.5,  34. ,  52.5],
                                [  0. ,  20.5,  42. ,  64.5]]])

        assert_allclose(y_int, y_expected)

        # Try with all axes
        shapes = [(2, 2, 4), (3, 1, 4), (3, 2, 3)]
        for axis, shape in zip([0, 1, 2], shapes):
            y_int = cumtrapz(y, x, initial=3.45, axis=axis)
            assert_equal(y_int.shape, (3, 2, 4))
            y_int = cumtrapz(y, x, initial=None, axis=axis)
            assert_equal(y_int.shape, shape)

    def test_x_none(self):
        y = np.linspace(-2, 2, num=5)

        y_int = cumtrapz(y)
        y_expected = [-1.5, -2., -1.5, 0.]
        assert_allclose(y_int, y_expected)

        y_int = cumtrapz(y, initial=1.23)
        y_expected = [1.23, -1.5, -2., -1.5, 0.]
        assert_allclose(y_int, y_expected)

        y_int = cumtrapz(y, dx=3)
        y_expected = [-4.5, -6., -4.5, 0.]
        assert_allclose(y_int, y_expected)

        y_int = cumtrapz(y, dx=3, initial=1.23)
        y_expected = [1.23, -4.5, -6., -4.5, 0.]
        assert_allclose(y_int, y_expected)


if __name__ == "__main__":
    run_module_suite()
