trunk/libf/regr1_lint.f90

module regr1_lint_m

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