File: SCMA.FT of Tape: Various/ETH/eth11-1

(Source file text) 

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C     ..................................................................
C
C        SUBROUTINE SCMA
C
C        PURPOSE
C           MULTIPLY COLUMN OF MATRIX BY A SCALAR AND ADD TO ANOTHER
C           COLUMN OF THE SAME MATRIX
C
C        USAGE
C           CALL SCMA(A,C,N,LA,LB)
C
C        DESCRIPTION OF PARAMETERS
C           A  - NAME OF MATRIX
C           C  - SCALAR
C           N  - NUMBER OF ROWS IN A
C           LA - COLUMN IN A TO BE MULTIPLIED BY SCALAR
C           LB - COLUMN IN A TO WHICH PRODUCT IS ADDED
C                IF 0 IS SPECIFIED, PRODUCT REPLACES ELEMENTS IN LA
C
C        REMARKS
C           MATRIX A MUST BE A GENERAL MATRIX
C
C        SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED
C           NONE
C
C        METHOD
C           EACH ELEMENT OF COLUMN LA IS MULTIPLIED BY SCALAR C AND THE
C           PRODUCT IS ADDED TO THE CORRESPONDING ELEMENT OF COLUMN LB.
C           COLUMN LA REMAINS UNAFFECTED BY THE OPERATION.
C           IF PARAMETER LB CONTAINS ZERO, MULTIPLICATION BY THE SCALAR
C           IS PERFORMED AND THE PRODUCT REPLACES ELEMENTS IN LA.
C
C     ..................................................................
C
      SUBROUTINE SCMA(A,C,N,LA,LB)
      DIMENSION A(1)
C
C        LOCATE STARTING POINT OF BOTH COLUMNS
C
      ILA=N*(LA-1)
      ILB=N*(LB-1)
C
      DO 3 I=1,N
      ILA=ILA+1
      ILB=ILB+1
C
C        CHECK LB FOR ZERO
C
      IF(LB) 1,2,1
C
C        IF NOT MULTIPLY BY CONSTANT AND ADD TO SECOND COLUMN
C
    1 A(ILB)=A(ILA)*C+A(ILB)
      GO TO 3
C
C        OTHERWISE, MULTIPLY COLUMN BY CONSTANT
C
    2 A(ILA)=A(ILA)*C
    3 CONTINUE
      RETURN
      END
C

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