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| author | stainer_t <thomas.stainer@oecd-nea.org> | 2025-09-08 13:48:49 +0200 |
|---|---|---|
| committer | stainer_t <thomas.stainer@oecd-nea.org> | 2025-09-08 13:48:49 +0200 |
| commit | 7dfcc480ba1e19bd3232349fc733caef94034292 (patch) | |
| tree | 03ee104eb8846d5cc1a981d267687a729185d3f3 /Utilib/src/SDOT.f | |
Initial commit from Polytechnique Montreal
Diffstat (limited to 'Utilib/src/SDOT.f')
| -rw-r--r-- | Utilib/src/SDOT.f | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/Utilib/src/SDOT.f b/Utilib/src/SDOT.f new file mode 100644 index 0000000..c1f8897 --- /dev/null +++ b/Utilib/src/SDOT.f @@ -0,0 +1,76 @@ +*DECK SDOT + REAL FUNCTION SDOT(N,SX,INCX,SY,INCY) +* +*----------------------------------------------------------------------- +* +*Purpose: +* forms the dot product of two vectors. Uses unrolled loops for +* increments equal to one. +* +*Copyright: +* Copyright (C) 2002 Ecole Polytechnique de Montreal +* This library is free software; you can redistribute it and/or +* modify it under the terms of the GNU Lesser General Public +* License as published by the Free Software Foundation; either +* version 2.1 of the License, or (at your option) any later version +* +*Author(s): Jack Dongarra, linpack, 3/11/78. +* +*Parameters: input +* N number of components in the vectors. +* SX first vector. +* INCX increment in first vector. +* SY second vector. +* INCY increment in second vector. +* +*Parameters: output +* SDOT dot product. +* +*----------------------------------------------------------------------- +* +*---- +* SUBROUTINE ARGUMENTS +*---- + INTEGER N,INCX,INCY + REAL SX(N*INCX),SY(N*INCY) +*---- +* LOCAL VARIABLES +*---- + INTEGER I,IX,IY,M,MP1 + REAL STEMP +* + STEMP = 0.0E0 + SDOT = 0.0E0 + IF(N.LE.0)RETURN + IF(INCX.EQ.1.AND.INCY.EQ.1)GO TO 20 +*---- +* CODE FOR UNEQUAL INCREMENTS OR EQUAL INCREMENTS NOT EQUAL TO 1. +*---- + IX = 1 + IY = 1 + IF(INCX.LT.0)IX = (-N+1)*INCX + 1 + IF(INCY.LT.0)IY = (-N+1)*INCY + 1 + DO 10 I = 1,N + STEMP = STEMP + SX(IX)*SY(IY) + IX = IX + INCX + IY = IY + INCY + 10 CONTINUE + SDOT = STEMP + RETURN +*---- +* CODE FOR BOTH INCREMENTS EQUAL TO 1. CLEAN-UP LOOP. +*---- + 20 M = MOD(N,5) + IF( M .EQ. 0 ) GO TO 40 + DO 30 I = 1,M + STEMP = STEMP + SX(I)*SY(I) + 30 CONTINUE + IF( N .LT. 5 ) GO TO 60 + 40 MP1 = M + 1 + DO 50 I = MP1,N,5 + STEMP = STEMP + SX(I)*SY(I) + SX(I + 1)*SY(I + 1) + + * SX(I + 2)*SY(I + 2) + SX(I + 3)*SY(I + 3) + SX(I + 4)*SY(I + 4) + 50 CONTINUE + 60 SDOT = STEMP + RETURN + END |