DOUBLE PRECISION FUNCTION DINTSM (SXMIN) c Copyright (c) 1996 California Institute of Technology, Pasadena, CA. c ALL RIGHTS RESERVED. c Based on Government Sponsored Research NAS7-03001. C>> 1996-03-31 DINTSM Krogh Removed unused variable in common. c>> 1995-11-20 DINTSM Krogh Converted from SFTRAN to Fortran 77. c>> 1994-10-19 DINTSM Krogh Changes to use M77CON c>> 1994-07-07 DINTSM Snyder set up for CHGTYP. c>> 1994-07-05 DINTSM Snyder Corrected calculation C>> 1993-05-18 DINTSM Krogh -- Changed "END" to "END PROGRAM" C>> 1987-11-19 DINTSM Snyder Initial code. C c--D replaces "?": ?intc, ?intec, ?intnc, ?INTSM c C CALCULATE THE MINIMUM STEPSIZE TO USE IF ALOCAL WERE SET EQUAL TO C SXMIN. C C WRITE X = TA + (T-TA)**2/TB. IF WE LET X2 - X1 BE THE SMALLEST C ALLOWED STEP AT X1, SAY SMIN, THEN C TB*(X2-X1) = TB*SMIN = (T2-TA)**2 - (T1-TA)**2, OR C TB*SMIN = (T2-T1)*(T2-T1+2*(T1-TA)). SOLVING FOR T2-T1 PROVIDES C THE EXPRESSIONS IN THE CODE BELOW. THE ANALYSIS PROCEEDS C SIMILARLY WHEN X = TA + (T-TA)**4/TB**3. C DOUBLE PRECISION SXMIN C C ***** LOCAL VARIABLES ************************************ C C SG IS A TEMPORARY VARIABLE DOUBLE PRECISION SG C SMIN IS THE VALUE THAT WILL BE RETURNED AS THE MINIMUM STEPSIZE. DOUBLE PRECISION SMIN C SOLVE IS AN ARITHMETIC STATEMENT FUNCTION DEFINED BELOW. DOUBLE PRECISION SOLVE C SQRTTB IS SQRT(ABS(TB)) DOUBLE PRECISION SQRTTB C SX IS A LOCAL COPY OF SXMIN. DOUBLE PRECISION SX C TDECR IS AN ARITHMETIC STATEMENT FUNCTION DEFINED BELOW. DOUBLE PRECISION TDECR C C ***** COMMON VARIABLES *********************************** C C COMMON /DINTNC/ CONTAINS VARIABLES NOT SEPARATELY SAVED FOR C EACH DIMENSION OF A MULTIPLE QUADRATURE. COMMON /DINTC/ C CONTAINS VARIABLES THAT MUST BE SAVED FOR EACH DIMENSION OF THE C QUADRATURE. THE VARIABLES IN EACH COMMON BLOCK ARE STORED IN THE C ORDER - ALWAYS DOUBLE, DOUBLE IF DOUBLE PRECISION PROGRAM, DOUBLE C IF DOUBLE PRECISION PROGRAM AND EXPONENT RANGE OF DOUBLE AND C SINGLE VERY DIFFERENT, SINGLE, INTEGER, LOGICAL. A PAD OF LOGICAL C VARIABLES IS INCLUDED AT THE END OF /DINTC/. THE DIMENSION OF C THE PAD MAY NEED TO BE VARIED SO THAT NO VARIABLES BEYOND THE END C OF THE COMMON BLOCK ARE ALTERED. C C DECLARATIONS OF COMMON /DINTNC/ VARIABLES. C DOUBLE PRECISION AINIT, BINIT, FNCVAL, S, TP DOUBLE PRECISION FER, FER1, RELOBT, TPS, XJ, XJP INTEGER FEA, FEA1, INC, INC2, IPRINT, 1 ISTOP(2,2),JPRINT, KDIM, KK, KMAXF, NDIM, 2 NFINDX, NFMAX, NFMAXM, RELTOL, REVERM, REVERS, 3 WHEREM LOGICAL NEEDH C C DECLARATIONS OF COMMON /DINTC/ VARIABLES. C c--D Next line special: S => D, X => Q, D => D, P => D DOUBLE PRECISION ACUM, PACUM, RESULT(2) C 139 $.TYPE.$ VARIABLES DOUBLE PRECISION 1 AACUM, ABSCIS, DELMIN, DELTA, DIFF, DISCX(2), 2 END(2), ERRINA, ERRINB, FAT(2), FSAVE, 3 FUNCT(24), F1, F2, LOCAL(4), PAACUM, PF1, 4 PF2, PHISUM, PHTSUM, PX, SPACE(6), 5 STEP(2), START(2), SUM, T, TA, TASAVE, 6 TB, TEND, WORRY(2), X, X1, 7 X2, XT(17), FT(17), PHI(34) c Note XT, FT, and PHI above are last, because they must be in adjacent c locations in DINTC. C 30 $DSTYP$ VARIABLES DOUBLE PRECISION 1 ABSDIF, COUNT, EDUE2A, EDUE2B, EP, EPNOIZ, 2 EPS, EPSMAX, EPSMIN, EPSO, EPSR, EPSS, 3 ERR, ERRAT(2), ERRC, ERRF, ERRI, ERRT(2), 4 ESOLD, EXTRA, PEPSMN, RE, RELEPS, REP, 5 REPROD, RNDC, TLEN, XJUMP C 29 INTEGER VARIABLES INTEGER DISCF, DISCHK, ENDPTS, I, INEW, 1 IOLD, IP, IXKDIM, J, J1, J1OLD, 2 J2, J2OLD, K, KAIMT, KMAX, KMIN, 3 L, LENDT, NFEVAL, NFJUMP, NSUB, NSUBSV, 4 NXKDIM, PART, SEARCH, TALOC, WHERE, WHERE2 C 11 TO 18 LOGICALS (7 ARE PADDING). LOGICAL DID1, FAIL, FATS(2), FSAVED, HAVDIF, 1 IEND, INIT, ROUNDF, XCDOBT(2), PAD(7) C C THE COMMON BLOCKS. C COMMON /DINTNC/ c 1 2 3 4 5 6 7 8 W AINIT, BINIT, FNCVAL, S, TP, FER, FER1, RELOBT, c 9 10 11 12 13 1 2 3 X TPS, XJ, XJP, FEA, FEA1, KDIM, INC, INC2, c 4 (2,2) 8 9 10 11 12 13 14 Y ISTOP, JPRINT, IPRINT, KK, KMAXF, NDIM, NFINDX, NFMAX, c 15 16 17 18 19 20 Z NFMAXM, RELTOL, REVERM, REVERS, WHEREM, NEEDH COMMON /DINTC/ 1 ACUM, PACUM, RESULT COMMON /DINTC/ c 1 2 (4) 6 7 8 9 10 11 (2) 1 AACUM, LOCAL, ABSCIS, TA, DELTA, DELMIN, DIFF, DISCX, c 13 (2) 15 16 17 (2) 19 20 (24) 44 2 END, ERRINA, ERRINB, FAT, FSAVE, FUNCT, F2, c 45 46 47 48 49 50 51 (6) 3 PAACUM, PF1, PF2, PHISUM, PHTSUM, PX, SPACE, c 57 (2) 59 (2) 61 62 63 64 65 4 STEP, START, SUM, T, TASAVE, TB, TEND, c 66 (2) 68 69 70 71 72 5 WORRY, X1, X2, X, F1, COUNT, c 73 (17) 90 (17) 107 (34) 6 XT, FT, PHI COMMON /DINTC/ c 141 142 143 144 145 146 1 ABSDIF, EDUE2A, EDUE2B, EP, EPNOIZ, EPSMAX, c 147 148 149 150 (2) 152 153 2 EPSO, EPSR, EPSS, ERRAT, ERRC, ERRF, c 154 (2) 156 157 158 159 160 3 ERRT, ESOLD, EXTRA, PEPSMN, RELEPS, REP, c 161 162 163 4 RNDC, TLEN, XJUMP, c 164 165 166 167 168 169 5 ERRI, ERR, EPSMIN, EPS, RE, REPROD COMMON /DINTC/ c 170 171 172 1 DISCF, DISCHK, ENDPTS, INEW, IOLD, IP, IXKDIM, 2 J, J1, J1OLD, J2, J2OLD, KMAX, KMIN, 3 L, LENDT, NFJUMP, NSUBSV, NXKDIM, TALOC, WHERE2, c 1 2 3 4 5 6 7 8 4 I, K, KAIMT, NSUB, PART, SEARCH, WHERE, NFEVAL COMMON /DINTC/ 1 DID1, FAIL, FATS, FSAVED, HAVDIF, IEND, INIT, ROUNDF, 2 XCDOBT, PAD SAVE /DINTNC/, /DINTC/ C C THE VARIABLES HERE DEFINE THE MACHINE ENVIRONMENT. ALL ARE SET C IN DINTOP. THE MEANING ATTACHED TO THESE VARIABLES CAN BE C FOUND BY LOOKING AT THE DEFINITIONS IN DINTOP. DOUBLE PRECISION 1 EMEPS, EEPSM8, EDELM2, EDELM3, ESQEPS, ERSQEP, ERSQE6, EMINF, 2 ESMALL, ENZER, EDELM1, ENINF COMMON /DINTEC/ 1 EMEPS, EEPSM8, EDELM2, EDELM3, ESQEPS, ERSQEP, ERSQE6, EMINF, 2 ESMALL, ENZER, EDELM1, ENINF SAVE /DINTEC/ C C ***** STATEMENT FUNCTIONS ******************************** C C SOLVE PROVIDES THE SOLUTION OF A QUADRATIC EQUATION. SOLVE(SX,SG)=SQRTTB*SX/(SG*SQRTTB+SQRT(ABS(TB)*SG*SG+SX)) C TDECR IS USED TO TRANSFORM AN ABSCISSA FROM THE CURRENT COORDINATE C SYSTEM TO ONE IN WHICH NSUB IS DECREMENTED BY A FACTOR OF 2. C TDECR(SX)=TA+(SX-TA)*((SX-TA)/TB) TDECR(SX)=TA*(1.0+TA/TB)+SX*((SX-TA)/TB-TA/TB) C C ***** EXECUTABLE STATEMENTS ****************************** C SX=SXMIN IF (NSUB .EQ. 0) THEN SG = SX ELSE SG = TDECR(SX) IF (NSUB .NE. 2) SG = TDECR(SG) END IF SMIN=EDELM3*MAX(EDELM1,ABS(SG)) IF (NSUB .NE. 0) THEN SQRTTB=SQRT(ABS(TB)) SG = ABS((SX-TA)/TB) SMIN=SOLVE(SMIN,SG) IF (NSUB .NE. 2) SMIN=SOLVE(SMIN,SG*SG) END IF DINTSM=SMIN RETURN END