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module inifgn_m |
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use dimensions, only: iim |
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IMPLICIT NONE |
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private iim |
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real sddu(iim), sddv(iim) |
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! sdd[uv] = sqrt(2 pi / iim * (derivative of the longitudinal zoom |
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! function)(rlon[uv])) |
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real unsddu(iim), unsddv(iim) |
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contains |
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SUBROUTINE inifgn(eignval_v, eignfnu, eignfnv) |
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! From LMDZ4/libf/filtrez/inifgn.F, v 1.1.1.1 2004/05/19 12:53:09 |
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! Authors: H. Upadyaya, O. Sharma |
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! Computes the eigenvalues and eigenvectors of the discrete analog |
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! of the second derivative with respect to longitude. |
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USE dimensions, ONLY: iim |
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USE dynetat0_m, ONLY: xprimu, xprimv |
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use jumble, only: new_unit |
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use numer_rec_95, only: jacobi, eigsrt |
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real, intent(out):: eignval_v(:) ! (iim) |
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! eigenvalues sorted in descending order |
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real, intent(out):: eignfnu(:, :), eignfnv(:, :) ! (iim, iim) eigenvectors |
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! Local: |
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REAL delta(iim, iim) ! second derivative, symmetric, elements are angle^{-2} |
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REAL deriv_u(iim, iim), deriv_v(iim, iim) |
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! first derivative at u and v longitudes, elements are angle^{-1} |
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REAL eignval_u(iim) |
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INTEGER i, unit |
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!---------------------------------------------------------------- |
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print *, "Call sequence information: inifgn" |
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sddv = sqrt(xprimv(:iim)) |
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sddu = sqrt(xprimu(:iim)) |
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unsddu = 1. / sddu |
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unsddv = 1. / sddv |
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deriv_u = 0. |
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deriv_u(iim, 1) = unsddu(iim) * unsddv(1) |
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forall (i = 1:iim) deriv_u(i, i) = - unsddu(i) * unsddv(i) |
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forall (i = 1:iim - 1) deriv_u(i, i + 1) = unsddu(i) * unsddv(i + 1) |
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deriv_v = - transpose(deriv_u) |
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delta = matmul(deriv_v, deriv_u) ! second derivative at v longitudes |
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CALL jacobi(delta, eignval_v, eignfnv) |
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CALL eigsrt(eignval_v, eignfnv) |
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delta = matmul(deriv_u, deriv_v) ! second derivative at u longitudes |
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CALL jacobi(delta, eignval_u, eignfnu) |
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CALL eigsrt(eignval_u, eignfnu) |
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call new_unit(unit) |
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open(unit, file = "inifgn_out.txt", status = "replace", action = "write") |
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write(unit, fmt = *) '"eignval_v"', eignval_v |
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close(unit) |
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END SUBROUTINE inifgn |
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end module inifgn_m |
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