Revision **948ad5967298b4dc174f4d96511af60f38e9279e** authored by Roger Koenker on **27 July 2019, 09:38:23 UTC**, committed by cran-robot on **27 July 2019, 09:38:23 UTC**

srtpai.f

```
SUBROUTINE SRTPAI ( A, SA, P, SP, N )
C
C SRTPAI SETS P(1) = 1, P(SP+1) = 2, ..., P((N-1)*SP+1) = N
C AND THEN REARRANGES P(1), P(SP+1), ..., P((N-1)*SP+1) SO THAT
C A( (P(I)-1)*SA+1 ) .LE. A( (P(J)-1)*SA+1 ) IF AND ONLY IF
C I .LT. J, WHERE I AND J SUBSCRIPT PROPER ELEMENTS OF P
C
INTEGER SP, P(SP, *), SA, H, PIH, PI
INTEGER A(SA, *)
C
C CHECK INPUT PARAMETERS AND INITIALIZE H
C
CALL I1SRT( SA, SP, N )
IF ( I0SRT( 1, N, H ) .LT. 1 ) RETURN
C
C INITIALIZE P
C
DO 10 I = 1, N
10 P(1, I) = I
C
C CHECK IF DONE WITH SORT
C
20 IF ( H .LT. 1 ) RETURN
K = N - H
C
C COMPARE
C
DO 40 J = 1, K
I = J
30 IH = I + H
PI = P(1, I)
PIH = P(1, IH)
IF ( A(1, PI) .LE. A(1, PIH) ) GOTO 40
C
C EXCHANGE
C
P(1, I) = PIH
P(1, IH) = PI
C
C PERCOLATE EXCHANGED LIST ELEMENT UP TO PROPER PLACE
C
I = I - H
IF ( I .GE. 1 ) GOTO 30
40 CONTINUE
C
H = ( H - 1 ) / 3
GOTO 20
C
END
SUBROUTINE I1SRT ( SA, SP, N )
C
C I1SRT CHECKS LEGALITY OF VALUES OF SA, SP, N
C
INTEGER SA, SP
C
C/6S
C IF ( N .LT. 0 )
C 1 CALL SETERR( 27HSRTXXX - ILLEGAL VALUE OF N, 27, 1, 2 )
C IF ( SA .LE. 0 )
C 1 CALL SETERR( 28HSRTXXX - ILLEGAL VALUE OF SA, 28, 2, 2 )
C IF ( SP .LE. 0 )
C 1 CALL SETERR( 28HSRTXXX - ILLEGAL VALUE OF SP, 28, 3, 2 )
C/7S
C IF ( N .LT. 0 )
C 1 CALL SETERR( 'SRTXXX - ILLEGAL VALUE OF N', 27, 1, 2 )
C IF ( SA .LE. 0 )
C 1 CALL SETERR( 'SRTXXX - ILLEGAL VALUE OF SA', 28, 2, 2 )
C IF ( SP .LE. 0 )
C 1 CALL SETERR( 'SRTXXX - ILLEGAL VALUE OF SP', 28, 3, 2 )
C/
C
RETURN
C
END
INTEGER FUNCTION I0SRT ( SA, N, H )
C
C I0SRT CHECKS INPUT PARAMETERS N, SA AND CALCULATES H
C RETURNS H = 0 IF NO SORTING NECESSARY, ELSE
C RETURNS SPACING, H, FOR FIRST INSERTION SORT.
C I0SRT RETURNS TOTAL NUMBER OF ELEMENTS IN ARRAY = N * SA
C
INTEGER SA, H
C
C/6S
C IF ( N .LT. 0 )
C 1 CALL SETERR( 27HSRTXXX - ILLEGAL VALUE OF N, 27, 1, 2 )
C IF ( SA .LE. 0 )
C 1 CALL SETERR( 28HSRTXXX - ILLEGAL VALUE OF SA, 28, 2, 2 )
C/7S
C IF ( N .LT. 0 )
C 1 CALL SETERR( 'SRTXXX - ILLEGAL VALUE OF N', 27, 1, 2 )
C IF ( SA .LE. 0 )
C 1 CALL SETERR( 'SRTXXX - ILLEGAL VALUE OF SA', 28, 2, 2 )
C/
C
C CHECK IF SORTING IS NECESSARY
C
H = 0
I0SRT = N * SA
IF ( N .LE. 1 ) RETURN
C
C CALCULATE H USING H NEW = 3 * H OLD + SA
C
H = 4 * SA
C
10 H = 3 * H + SA
IF ( H .LT. I0SRT ) GOTO 10
C
H = ( H - 4 * SA ) / 9
C
RETURN
C
END
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