src/functions.f90

   1 MODULE functions
   2
   3   real(kind=8), private, parameter :: poly_coeffs(11) =            &
   4        [-11.0, 15.6, -4.6, 22.5, 8.1, 5.1, -0.3, -8.0, 0.0, -9.9, 2.2]
   5
   6   INTERFACE
   7      FUNCTION analytical_integral(ibeg, iend) result(y)
   8        real(kind=8), intent(in) :: ibeg, iend
   9        real(kind=8) :: y
  10      END FUNCTION analytical_integral
  11   END INTERFACE
  12
  13 CONTAINS
  14
  15   FUNCTION my_exp(x) result(y)
  16     real(kind=8), intent(in) :: x
  17     real(kind=8) :: y
  18     y = exp(x)
  19   END FUNCTION my_exp
  20
  21   FUNCTION my_sin(x) result(y)
  22     real(kind=8), intent(in) :: x
  23     real(kind=8) :: y
  24     y = sin(x)
  25   END FUNCTION my_sin
  26
  27   FUNCTION my_poly(x) result(y)
  28     real(kind=8), intent(in) :: x
  29     real(kind=8) :: y
  30     integer(kind=4) :: i
  31     y = sum(poly_coeffs(:) * [1.0_8, (x ** [(i, i = 1, 10)])])
  32   END FUNCTION my_poly
  33
  34   FUNCTION my_exp_int(ibeg, iend) result(y)
  35     real(kind=8), intent(in) :: ibeg, iend
  36     real(kind=8) :: y
  37     y = exp(iend) - exp(ibeg)
  38   END FUNCTION my_exp_int
  39
  40   FUNCTION my_sin_int(ibeg, iend) result(y)
  41     real(kind=8), intent(in) :: ibeg, iend
  42     real(kind=8) :: y
  43     y = -cos(iend) + cos(ibeg)
  44   END FUNCTION my_sin_int
  45
  46   FUNCTION my_poly_int_indefinite(x) result(y)
  47     real(kind=8), intent(in) :: x
  48     real(kind=8) :: y
  49     integer(kind=4) :: i, j
  50     y = sum(poly_coeffs(:) * (1 / real([(j, j = 1, 11)])) *        &
  51          (x ** [(i, i = 1, 11)]))
  52   END FUNCTION my_poly_int_indefinite
  53
  54   FUNCTION my_poly_int(ibeg, iend) result(y)
  55     real(kind=8), intent(in) :: ibeg, iend
  56     real(kind=8) :: y
  57     y = my_poly_int_indefinite(iend) - my_poly_int_indefinite(ibeg)
  58   END FUNCTION my_poly_int
  59
  60 END MODULE functions