| Brian Silverman | 72890c2 | 2015-09-19 14:37:37 -0400 | [diff] [blame] | 1 | SUBROUTINE DROTMG(DD1,DD2,DX1,DY1,DPARAM) |
| 2 | * .. Scalar Arguments .. |
| 3 | DOUBLE PRECISION DD1,DD2,DX1,DY1 |
| 4 | * .. |
| 5 | * .. Array Arguments .. |
| 6 | DOUBLE PRECISION DPARAM(5) |
| 7 | * .. |
| 8 | * |
| 9 | * Purpose |
| 10 | * ======= |
| 11 | * |
| 12 | * CONSTRUCT THE MODIFIED GIVENS TRANSFORMATION MATRIX H WHICH ZEROS |
| 13 | * THE SECOND COMPONENT OF THE 2-VECTOR (DSQRT(DD1)*DX1,DSQRT(DD2)* |
| 14 | * DY2)**T. |
| 15 | * WITH DPARAM(1)=DFLAG, H HAS ONE OF THE FOLLOWING FORMS.. |
| 16 | * |
| 17 | * DFLAG=-1.D0 DFLAG=0.D0 DFLAG=1.D0 DFLAG=-2.D0 |
| 18 | * |
| 19 | * (DH11 DH12) (1.D0 DH12) (DH11 1.D0) (1.D0 0.D0) |
| 20 | * H=( ) ( ) ( ) ( ) |
| 21 | * (DH21 DH22), (DH21 1.D0), (-1.D0 DH22), (0.D0 1.D0). |
| 22 | * LOCATIONS 2-4 OF DPARAM CONTAIN DH11, DH21, DH12, AND DH22 |
| 23 | * RESPECTIVELY. (VALUES OF 1.D0, -1.D0, OR 0.D0 IMPLIED BY THE |
| 24 | * VALUE OF DPARAM(1) ARE NOT STORED IN DPARAM.) |
| 25 | * |
| 26 | * THE VALUES OF GAMSQ AND RGAMSQ SET IN THE DATA STATEMENT MAY BE |
| 27 | * INEXACT. THIS IS OK AS THEY ARE ONLY USED FOR TESTING THE SIZE |
| 28 | * OF DD1 AND DD2. ALL ACTUAL SCALING OF DATA IS DONE USING GAM. |
| 29 | * |
| 30 | * |
| 31 | * Arguments |
| 32 | * ========= |
| 33 | * |
| 34 | * DD1 (input/output) DOUBLE PRECISION |
| 35 | * |
| 36 | * DD2 (input/output) DOUBLE PRECISION |
| 37 | * |
| 38 | * DX1 (input/output) DOUBLE PRECISION |
| 39 | * |
| 40 | * DY1 (input) DOUBLE PRECISION |
| 41 | * |
| 42 | * DPARAM (input/output) DOUBLE PRECISION array, dimension 5 |
| 43 | * DPARAM(1)=DFLAG |
| 44 | * DPARAM(2)=DH11 |
| 45 | * DPARAM(3)=DH21 |
| 46 | * DPARAM(4)=DH12 |
| 47 | * DPARAM(5)=DH22 |
| 48 | * |
| 49 | * ===================================================================== |
| 50 | * |
| 51 | * .. Local Scalars .. |
| 52 | DOUBLE PRECISION DFLAG,DH11,DH12,DH21,DH22,DP1,DP2,DQ1,DQ2,DTEMP, |
| 53 | + DU,GAM,GAMSQ,ONE,RGAMSQ,TWO,ZERO |
| 54 | INTEGER IGO |
| 55 | * .. |
| 56 | * .. Intrinsic Functions .. |
| 57 | INTRINSIC DABS |
| 58 | * .. |
| 59 | * .. Data statements .. |
| 60 | * |
| 61 | DATA ZERO,ONE,TWO/0.D0,1.D0,2.D0/ |
| 62 | DATA GAM,GAMSQ,RGAMSQ/4096.D0,16777216.D0,5.9604645D-8/ |
| 63 | * .. |
| 64 | |
| 65 | IF (.NOT.DD1.LT.ZERO) GO TO 10 |
| 66 | * GO ZERO-H-D-AND-DX1.. |
| 67 | GO TO 60 |
| 68 | 10 CONTINUE |
| 69 | * CASE-DD1-NONNEGATIVE |
| 70 | DP2 = DD2*DY1 |
| 71 | IF (.NOT.DP2.EQ.ZERO) GO TO 20 |
| 72 | DFLAG = -TWO |
| 73 | GO TO 260 |
| 74 | * REGULAR-CASE.. |
| 75 | 20 CONTINUE |
| 76 | DP1 = DD1*DX1 |
| 77 | DQ2 = DP2*DY1 |
| 78 | DQ1 = DP1*DX1 |
| 79 | * |
| 80 | IF (.NOT.DABS(DQ1).GT.DABS(DQ2)) GO TO 40 |
| 81 | DH21 = -DY1/DX1 |
| 82 | DH12 = DP2/DP1 |
| 83 | * |
| 84 | DU = ONE - DH12*DH21 |
| 85 | * |
| 86 | IF (.NOT.DU.LE.ZERO) GO TO 30 |
| 87 | * GO ZERO-H-D-AND-DX1.. |
| 88 | GO TO 60 |
| 89 | 30 CONTINUE |
| 90 | DFLAG = ZERO |
| 91 | DD1 = DD1/DU |
| 92 | DD2 = DD2/DU |
| 93 | DX1 = DX1*DU |
| 94 | * GO SCALE-CHECK.. |
| 95 | GO TO 100 |
| 96 | 40 CONTINUE |
| 97 | IF (.NOT.DQ2.LT.ZERO) GO TO 50 |
| 98 | * GO ZERO-H-D-AND-DX1.. |
| 99 | GO TO 60 |
| 100 | 50 CONTINUE |
| 101 | DFLAG = ONE |
| 102 | DH11 = DP1/DP2 |
| 103 | DH22 = DX1/DY1 |
| 104 | DU = ONE + DH11*DH22 |
| 105 | DTEMP = DD2/DU |
| 106 | DD2 = DD1/DU |
| 107 | DD1 = DTEMP |
| 108 | DX1 = DY1*DU |
| 109 | * GO SCALE-CHECK |
| 110 | GO TO 100 |
| 111 | * PROCEDURE..ZERO-H-D-AND-DX1.. |
| 112 | 60 CONTINUE |
| 113 | DFLAG = -ONE |
| 114 | DH11 = ZERO |
| 115 | DH12 = ZERO |
| 116 | DH21 = ZERO |
| 117 | DH22 = ZERO |
| 118 | * |
| 119 | DD1 = ZERO |
| 120 | DD2 = ZERO |
| 121 | DX1 = ZERO |
| 122 | * RETURN.. |
| 123 | GO TO 220 |
| 124 | * PROCEDURE..FIX-H.. |
| 125 | 70 CONTINUE |
| 126 | IF (.NOT.DFLAG.GE.ZERO) GO TO 90 |
| 127 | * |
| 128 | IF (.NOT.DFLAG.EQ.ZERO) GO TO 80 |
| 129 | DH11 = ONE |
| 130 | DH22 = ONE |
| 131 | DFLAG = -ONE |
| 132 | GO TO 90 |
| 133 | 80 CONTINUE |
| 134 | DH21 = -ONE |
| 135 | DH12 = ONE |
| 136 | DFLAG = -ONE |
| 137 | 90 CONTINUE |
| 138 | GO TO IGO(120,150,180,210) |
| 139 | * PROCEDURE..SCALE-CHECK |
| 140 | 100 CONTINUE |
| 141 | 110 CONTINUE |
| 142 | IF (.NOT.DD1.LE.RGAMSQ) GO TO 130 |
| 143 | IF (DD1.EQ.ZERO) GO TO 160 |
| 144 | ASSIGN 120 TO IGO |
| 145 | * FIX-H.. |
| 146 | GO TO 70 |
| 147 | 120 CONTINUE |
| 148 | DD1 = DD1*GAM**2 |
| 149 | DX1 = DX1/GAM |
| 150 | DH11 = DH11/GAM |
| 151 | DH12 = DH12/GAM |
| 152 | GO TO 110 |
| 153 | 130 CONTINUE |
| 154 | 140 CONTINUE |
| 155 | IF (.NOT.DD1.GE.GAMSQ) GO TO 160 |
| 156 | ASSIGN 150 TO IGO |
| 157 | * FIX-H.. |
| 158 | GO TO 70 |
| 159 | 150 CONTINUE |
| 160 | DD1 = DD1/GAM**2 |
| 161 | DX1 = DX1*GAM |
| 162 | DH11 = DH11*GAM |
| 163 | DH12 = DH12*GAM |
| 164 | GO TO 140 |
| 165 | 160 CONTINUE |
| 166 | 170 CONTINUE |
| 167 | IF (.NOT.DABS(DD2).LE.RGAMSQ) GO TO 190 |
| 168 | IF (DD2.EQ.ZERO) GO TO 220 |
| 169 | ASSIGN 180 TO IGO |
| 170 | * FIX-H.. |
| 171 | GO TO 70 |
| 172 | 180 CONTINUE |
| 173 | DD2 = DD2*GAM**2 |
| 174 | DH21 = DH21/GAM |
| 175 | DH22 = DH22/GAM |
| 176 | GO TO 170 |
| 177 | 190 CONTINUE |
| 178 | 200 CONTINUE |
| 179 | IF (.NOT.DABS(DD2).GE.GAMSQ) GO TO 220 |
| 180 | ASSIGN 210 TO IGO |
| 181 | * FIX-H.. |
| 182 | GO TO 70 |
| 183 | 210 CONTINUE |
| 184 | DD2 = DD2/GAM**2 |
| 185 | DH21 = DH21*GAM |
| 186 | DH22 = DH22*GAM |
| 187 | GO TO 200 |
| 188 | 220 CONTINUE |
| 189 | IF (DFLAG) 250,230,240 |
| 190 | 230 CONTINUE |
| 191 | DPARAM(3) = DH21 |
| 192 | DPARAM(4) = DH12 |
| 193 | GO TO 260 |
| 194 | 240 CONTINUE |
| 195 | DPARAM(2) = DH11 |
| 196 | DPARAM(5) = DH22 |
| 197 | GO TO 260 |
| 198 | 250 CONTINUE |
| 199 | DPARAM(2) = DH11 |
| 200 | DPARAM(3) = DH21 |
| 201 | DPARAM(4) = DH12 |
| 202 | DPARAM(5) = DH22 |
| 203 | 260 CONTINUE |
| 204 | DPARAM(1) = DFLAG |
| 205 | RETURN |
| 206 | END |