Skip to main content
`Ctrl`+`K`

# numpy.polynomial.hermite_e.hermeint

polynomial.hermite_e.hermeint(c, m=1, k=[], lbnd=0, scl=1, axis=0)

  Integrate a Hermite_e series.

  Returns the Hermite_e series coefficients c integrated m times from lbnd along axis. At each iteration the resulting series is multiplied by scl and an integration constant, k, is added. The scaling factor is for use in a linear change of variable. (“Buyer beware”: note that, depending on what one is doing, one may want scl to be the reciprocal of what one might expect; for more information, see the Notes section below.) The argument c is an array of coefficients from low to high degree along each axis, e.g., [1,2,3] represents the series `H_0 + 2*H_1 + 3*H_2` while [[1,2],[1,2]] represents `1*H_0(x)*H_0(y) + 1*H_1(x)*H_0(y) + 2*H_0(x)*H_1(y) + 2*H_1(x)*H_1(y)` if axis=0 is `x` and axis=1 is `y`.

  Parameters:
    c array_like

      Array of Hermite_e series coefficients. If c is multidimensional the different axis correspond to different variables with the degree in each axis given by the corresponding index.

    m int, optional

      Order of integration, must be positive. (Default: 1)

    k{[], list, scalar}, optional

      Integration constant(s). The value of the first integral at `lbnd` is the first value in the list, the value of the second integral at `lbnd` is the second value, etc. If `k == []` (the default), all constants are set to zero. If `m == 1`, a single scalar can be given instead of a list.

    lbnd scalar, optional

      The lower bound of the integral. (Default: 0)

    scl scalar, optional

      Following each integration the result is multiplied by scl before the integration constant is added. (Default: 1)

    axis int, optional

      Axis over which the integral is taken. (Default: 0).

  Returns:
    S ndarray

      Hermite_e series coefficients of the integral.

  Raises:
    ValueError

      If `m < 0`, `len(k) > m`, `np.ndim(lbnd) != 0`, or `np.ndim(scl) != 0`.

  See also

  `hermeder`

  Notes

  Note that the result of each integration is multiplied by scl. Why is this important to note? Say one is making a linear change of variable \(u = ax + b\) in an integral relative to x. Then \(dx = du/a\), so one will need to set scl equal to \(1/a\) - perhaps not what one would have first thought.

  Also note that, in general, the result of integrating a C-series needs to be “reprojected” onto the C-series basis set. Thus, typically, the result of this function is “unintuitive,” albeit correct; see Examples section below.

  Examples

      >>> from numpy.polynomial.hermite_e import hermeint
      >>> hermeint([1, 2, 3]) # integrate once, value 0 at 0.
      array([1., 1., 1., 1.])
      >>> hermeint([1, 2, 3], m=2) # integrate twice, value & deriv 0 at 0
      array([-0.25      ,  1.        ,  0.5       ,  0.33333333,  0.25      ]) # may vary
      >>> hermeint([1, 2, 3], k=1) # integrate once, value 1 at 0.
      array([2., 1., 1., 1.])
      >>> hermeint([1, 2, 3], lbnd=-1) # integrate once, value 0 at -1
      array([-1.,  1.,  1.,  1.])
      >>> hermeint([1, 2, 3], m=2, k=[1, 2], lbnd=-1)
      array([ 1.83333333,  0.        ,  0.5       ,  0.33333333,  0.25      ]) # may vary