M107 Sort Rows of a Matrix

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M107 Sort Rows of a Matrix

Routine ID: M107
Author(s): F. Carminati	Library: KERNLIB
Submitter:	Submitted: 09.02.1989
Language: Fortran	Revised:

SORTR re-arranges the row order of a matrix in such a way that the elements of a selected column are either in increasing or decreasing order as described. When these elements are equal, the rows are kept in their original order.

Structure:

SUBROUTINE subprogram
User Entry Names: SORTR, SORTI, SORTD
External References: VECMAN (F121), USWOP (V301) (not on all machines)

Usage:

For $t=I$ (type INTEGER), $t=R$ (type REAL), $t=D$ (type DOUBLE PRECISION),

    CALL SORTt(MX,NC,NR,NCS)

performs an ordering operation on the matrix MX of type t, dimensioned (NC,NR), using the NCS-th element of each row as ordering criterion.

The matrix MX is stored by rows, the first element of a row following immediately after the last element of the preceding row.

Obviously, $1 ≤|NCS| ≤NC$ is a condition. If this is not met or if $NR ≤1$ , SORTX will do nothing.

If $NCS > 0$ , the subroutine re-orders the rows of MX in such a way that the NCS-th element of each row is greater than or equal to the NCS-th element of the preceding row. If $NCS < 0$ , the rows of MX are re-ordered in such a way that the NCS-th element of each row is smaller than or equal to the NCS-th element of the preceding row.
$•$

M109

Janne Saarela
Mon Apr 3 15:06:23 METDST 1995