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# komasaru/regression_curve_3d.f95

Created May 8, 2019 01:46
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Fortran 95 source code to calculate a simple regression curve.(3d)
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 !**************************************************** ! 単回帰曲線（3次回帰）計算 ! : y = a + b * x + c * x^2 + d * x^3 ! : 連立方程式を ガウスの消去法で解く方法 ! date name version ! 2019.04.15 mk-mode.com 1.00 新規作成 ! ! Copyright(C) 2019 mk-mode.com All Rights Reserved. !**************************************************** ! module const ! SP: 単精度(4), DP: 倍精度(8) integer, parameter :: SP = kind(1.0) integer(SP), parameter :: DP = selected_real_kind(2 * precision(1.0_SP)) end module const module comp use const implicit none private public :: calc_reg_curve_3d contains ! 単回帰曲線（3次回帰）計算 ! ! :param(in) real(8) x(:): 説明変数配列 ! :param(in) real(8) y(:): 目的変数配列 ! :param(out) real(8) a: 係数 a ! :param(out) real(8) b: 係数 b ! :param(out) real(8) c: 係数 c ! :param(out) real(8) d: 係数 d subroutine calc_reg_curve_3d(x, y, a, b, c, d) implicit none real(DP), intent(in) :: x(:), y(:) real(DP), intent(out) :: a, b, c, d integer(SP) :: size_x, size_y, i real(DP) :: sum_x, sum_x2, sum_x3, sum_x4, sum_x5, sum_x6 real(DP) :: sum_y, sum_xy, sum_x2y, sum_x3y real(DP) :: mtx(4, 5) size_x = size(x) size_y = size(y) if (size_x == 0 .or. size_y == 0) then print *, "[ERROR] array size == 0" stop end if if (size_x /= size_y) then print *, "[ERROR] size(X) != size(Y)" stop end if sum_x = sum(x) sum_x2 = sum(x * x) sum_x3 = sum(x * x * x) sum_x4 = sum(x * x * x * x) sum_x5 = sum(x * x * x * x * x) sum_x6 = sum(x * x * x * x * x * x) sum_y = sum(y) sum_xy = sum(x * y) sum_x2y = sum(x * x * y) sum_x3y = sum(x * x * x * y) mtx(1, :) = (/real(size_x, DP), sum_x, sum_x2, sum_x3, sum_y/) mtx(2, :) = (/ sum_x, sum_x2, sum_x3, sum_x4, sum_xy/) mtx(3, :) = (/ sum_x2, sum_x3, sum_x4, sum_x5, sum_x2y/) mtx(4, :) = (/ sum_x3, sum_x4, sum_x5, sum_x6, sum_x3y/) call solve_ge(4, mtx) a = mtx(1, 5) b = mtx(2, 5) c = mtx(3, 5) d = mtx(4, 5) end subroutine calc_reg_curve_3d ! 連立方程式を解く（ガウスの消去法） ! ! :param(in) integer(4) n: 元数 ! :param(inout) real(8) a(n,n+1): 係数配列 subroutine solve_ge(n, a) implicit none integer(SP), intent(in) :: n real(DP), intent(inout) :: a(n, n + 1) integer(SP) :: i, j real(DP) :: d ! 前進消去 do j = 1, n - 1 do i = j + 1, n d = a(i, j) / a(j, j) a(i, j+1:n+1) = a(i, j+1:n+1) - a(j, j+1:n+1) * d end do end do ! 後退代入 do i = n, 1, -1 d = a(i, n + 1) do j = i + 1, n d = d - a(i, j) * a(j, n + 1) end do a(i, n + 1) = d / a(i, i) end do end subroutine solve_ge end module comp program regression_curve_3d use const use comp implicit none character(9), parameter :: F_INP = "input.txt" integer(SP), parameter :: UID = 10 real(DP) :: a, b, c, d integer(SP) :: n, i character(20) :: f real(DP), allocatable :: x(:), y(:) ! IN ファイル OPEN open (UID, file = F_INP, status = "old") ! データ数読み込み read (UID, *) n ! 配列用メモリ確保 allocate(x(n)) allocate(y(n)) ! データ読み込み do i = 1, n read (UID, *) x(i), y(i) end do write (f, '("(A, ", I0, "F8.2, A)")') n print f, "説明変数 X = (", x, ")" print f, "目的変数 Y = (", y, ")" print '(A)', "---" ! IN ファイル CLOSE close (UID) ! 回帰曲線計算 call calc_reg_curve_3d(x, y, a, b, c, d) print '(A, F12.8)', "a = ", a print '(A, F12.8)', "b = ", b print '(A, F12.8)', "c = ", c print '(A, F12.8)', "d = ", d ! 配列用メモリ解放 deallocate(x) deallocate(y) end program regression_curve_3d
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