trunk/libf/regr1_lint.f90

module regr1_lint_m

  ! Author: Lionel GUEZ

  implicit none

  interface regr1_lint
     ! Each procedure regrids by linear interpolation.
     ! The regridding operation is done on the first dimension of the
     ! input array.
     ! The difference betwwen the procedures is the rank of the first argument.
     module procedure regr11_lint, regr12_lint
  end interface

  private
  public regr1_lint

contains

  function regr11_lint(vs, xs, xt) result(vt)

    ! "vs" has rank 1.

    use nr_util, only: assert_eq
    use numer_rec, only: hunt !!, polint

    real, intent(in):: vs(:)
    ! (values of the function at source points "xs")

    real, intent(in):: xs(:)
    ! (abscissas of points in source grid, in strictly monotonic order)

    real, intent(in):: xt(:)
    ! (abscissas of points in target grid)

    real vt(size(xt)) ! values of the function on the target grid

    ! Variables local to the procedure:
    integer is, it, ns
    integer is_b ! "is" bound between 1 and "ns - 1"

    !--------------------------------------

    ns = assert_eq(size(vs), size(xs), "regr11_lint ns")

    is = -1 ! go immediately to bisection on first call to "hunt"

    do it = 1, size(xt)
       call hunt(xs, xt(it), is)
       is_b = min(max(is, 1), ns - 1)
!!       call polint(xs(is_b:is_b+1), vs(is_b:is_b+1), xt(it), vt(it))
       vt(it) = ((xs(is_b+1) - xt(it)) * vs(is_b) &
            + (xt(it) - xs(is_b)) * vs(is_b+1)) / (xs(is_b+1) - xs(is_b))
    end do

  end function regr11_lint

  !*********************************************************

  function regr12_lint(vs, xs, xt) result(vt)

    ! "vs" has rank 2.

    use nr_util, only: assert_eq
    use numer_rec, only: hunt

    real, intent(in):: vs(:, :)
    ! (values of the function at source points "xs")

    real, intent(in):: xs(:)
    ! (abscissas of points in source grid, in strictly monotonic order)

    real, intent(in):: xt(:)
    ! (abscissas of points in target grid)

    real vt(size(xt), size(vs, 2)) ! values of the function on the target grid

    ! Variables local to the procedure:
    integer is, it, ns
    integer is_b ! "is" bound between 1 and "ns - 1"

    !--------------------------------------

    ns = assert_eq(size(vs, 1), size(xs), "regr12_lint ns")

    is = -1 ! go immediately to bisection on first call to "hunt"

    do it = 1, size(xt)
       call hunt(xs, xt(it), is)
       is_b = min(max(is, 1), ns - 1)
       vt(it, :) = ((xs(is_b+1) - xt(it)) * vs(is_b, :) &
            + (xt(it) - xs(is_b)) * vs(is_b+1, :)) / (xs(is_b+1) - xs(is_b))
    end do

  end function regr12_lint

end module regr1_lint_m
1	guez	9	module regr1_lint_m
2
3	guez	36	! Author: Lionel GUEZ
4
5	guez	9	implicit none
6
7			interface regr1_lint
8			! Each procedure regrids by linear interpolation.
9			! The regridding operation is done on the first dimension of the
10			! input array.
11			! The difference betwwen the procedures is the rank of the first argument.
12			module procedure regr11_lint, regr12_lint
13			end interface
14
15			private
16			public regr1_lint
17
18			contains
19
20			function regr11_lint(vs, xs, xt) result(vt)
21
22			! "vs" has rank 1.
23
24	guez	36	use nr_util, only: assert_eq
25			use numer_rec, only: hunt !!, polint
26	guez	9
27			real, intent(in):: vs(:)
28			! (values of the function at source points "xs")
29
30			real, intent(in):: xs(:)
31			! (abscissas of points in source grid, in strictly monotonic order)
32
33			real, intent(in):: xt(:)
34			! (abscissas of points in target grid)
35
36			real vt(size(xt)) ! values of the function on the target grid
37
38			! Variables local to the procedure:
39			integer is, it, ns
40			integer is_b ! "is" bound between 1 and "ns - 1"
41
42			!--------------------------------------
43
44			ns = assert_eq(size(vs), size(xs), "regr11_lint ns")
45
46			is = -1 ! go immediately to bisection on first call to "hunt"
47
48			do it = 1, size(xt)
49			call hunt(xs, xt(it), is)
50			is_b = min(max(is, 1), ns - 1)
51	guez	13	!! call polint(xs(is_b:is_b+1), vs(is_b:is_b+1), xt(it), vt(it))
52			vt(it) = ((xs(is_b+1) - xt(it)) * vs(is_b) &
53			+ (xt(it) - xs(is_b)) * vs(is_b+1)) / (xs(is_b+1) - xs(is_b))
54	guez	9	end do
55
56			end function regr11_lint
57
58			!*********************************************************
59
60			function regr12_lint(vs, xs, xt) result(vt)
61
62			! "vs" has rank 2.
63
64	guez	36	use nr_util, only: assert_eq
65			use numer_rec, only: hunt
66	guez	9
67			real, intent(in):: vs(:, :)
68			! (values of the function at source points "xs")
69
70			real, intent(in):: xs(:)
71			! (abscissas of points in source grid, in strictly monotonic order)
72
73			real, intent(in):: xt(:)
74			! (abscissas of points in target grid)
75
76			real vt(size(xt), size(vs, 2)) ! values of the function on the target grid
77
78			! Variables local to the procedure:
79			integer is, it, ns
80			integer is_b ! "is" bound between 1 and "ns - 1"
81
82			!--------------------------------------
83
84			ns = assert_eq(size(vs, 1), size(xs), "regr12_lint ns")
85
86			is = -1 ! go immediately to bisection on first call to "hunt"
87
88			do it = 1, size(xt)
89			call hunt(xs, xt(it), is)
90			is_b = min(max(is, 1), ns - 1)
91			vt(it, :) = ((xs(is_b+1) - xt(it)) * vs(is_b, :) &
92			+ (xt(it) - xs(is_b)) * vs(is_b+1, :)) / (xs(is_b+1) - xs(is_b))
93			end do
94
95			end function regr12_lint
96
97			end module regr1_lint_m