3 /* Subroutine */ int dlaruv_(integer *iseed, integer *n, doublereal *x)
7 static integer mm[512] /* was [128][4] */ = { 494,2637,255,2008,1253,
8 3344,4084,1739,3143,3468,688,1657,1238,3166,1292,3422,1270,2016,
9 154,2862,697,1706,491,931,1444,444,3577,3944,2184,1661,3482,657,
10 3023,3618,1267,1828,164,3798,3087,2400,2870,3876,1905,1593,1797,
11 1234,3460,328,2861,1950,617,2070,3331,769,1558,2412,2800,189,287,
12 2045,1227,2838,209,2770,3654,3993,192,2253,3491,2889,2857,2094,
13 1818,688,1407,634,3231,815,3524,1914,516,164,303,2144,3480,119,
14 3357,837,2826,2332,2089,3780,1700,3712,150,2000,3375,1621,3090,
15 3765,1149,3146,33,3082,2741,359,3316,1749,185,2784,2202,2199,1364,
16 1244,2020,3160,2785,2772,1217,1822,1245,2252,3904,2774,997,2573,
17 1148,545,322,789,1440,752,2859,123,1848,643,2405,2638,2344,46,
18 3814,913,3649,339,3808,822,2832,3078,3633,2970,637,2249,2081,4019,
19 1478,242,481,2075,4058,622,3376,812,234,641,4005,1122,3135,2640,
20 2302,40,1832,2247,2034,2637,1287,1691,496,1597,2394,2584,1843,336,
21 1472,2407,433,2096,1761,2810,566,442,41,1238,1086,603,840,3168,
22 1499,1084,3438,2408,1589,2391,288,26,512,1456,171,1677,2657,2270,
23 2587,2961,1970,1817,676,1410,3723,2803,3185,184,663,499,3784,1631,
24 1925,3912,1398,1349,1441,2224,2411,1907,3192,2786,382,37,759,2948,
25 1862,3802,2423,2051,2295,1332,1832,2405,3638,3661,327,3660,716,
26 1842,3987,1368,1848,2366,2508,3754,1766,3572,2893,307,1297,3966,
27 758,2598,3406,2922,1038,2934,2091,2451,1580,1958,2055,1507,1078,
28 3273,17,854,2916,3971,2889,3831,2621,1541,893,736,3992,787,2125,
29 2364,2460,257,1574,3912,1216,3248,3401,2124,2762,149,2245,166,466,
30 4018,1399,190,2879,153,2320,18,712,2159,2318,2091,3443,1510,449,
31 1956,2201,3137,3399,1321,2271,3667,2703,629,2365,2431,1113,3922,
32 2554,184,2099,3228,4012,1921,3452,3901,572,3309,3171,817,3039,
33 1696,1256,3715,2077,3019,1497,1101,717,51,981,1978,1813,3881,76,
34 3846,3694,1682,124,1660,3997,479,1141,886,3514,1301,3604,1888,
35 1836,1990,2058,692,1194,20,3285,2046,2107,3508,3525,3801,2549,
36 1145,2253,305,3301,1065,3133,2913,3285,1241,1197,3729,2501,1673,
37 541,2753,949,2361,1165,4081,2725,3305,3069,3617,3733,409,2157,
38 1361,3973,1865,2525,1409,3445,3577,77,3761,2149,1449,3005,225,85,
39 3673,3117,3089,1349,2057,413,65,1845,697,3085,3441,1573,3689,2941,
40 929,533,2841,4077,721,2821,2249,2397,2817,245,1913,1997,3121,997,
41 1833,2877,1633,981,2009,941,2449,197,2441,285,1473,2741,3129,909,
42 2801,421,4073,2813,2337,1429,1177,1901,81,1669,2633,2269,129,1141,
43 249,3917,2481,3941,2217,2749,3041,1877,345,2861,1809,3141,2825,
44 157,2881,3637,1465,2829,2161,3365,361,2685,3745,2325,3609,3821,
45 3537,517,3017,2141,1537 };
47 /* System generated locals */
51 integer i__, i1, i2, i3, i4, it1, it2, it3, it4;
54 /* -- LAPACK auxiliary routine (version 3.1) -- */
55 /* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
58 /* .. Scalar Arguments .. */
60 /* .. Array Arguments .. */
66 /* DLARUV returns a vector of n random real numbers from a uniform (0,1) */
67 /* distribution (n <= 128). */
69 /* This is an auxiliary routine called by DLARNV and ZLARNV. */
74 /* ISEED (input/output) INTEGER array, dimension (4) */
75 /* On entry, the seed of the random number generator; the array */
76 /* elements must be between 0 and 4095, and ISEED(4) must be */
78 /* On exit, the seed is updated. */
80 /* N (input) INTEGER */
81 /* The number of random numbers to be generated. N <= 128. */
83 /* X (output) DOUBLE PRECISION array, dimension (N) */
84 /* The generated random numbers. */
89 /* This routine uses a multiplicative congruential method with modulus */
90 /* 2**48 and multiplier 33952834046453 (see G.S.Fishman, */
91 /* 'Multiplicative congruential random number generators with modulus */
92 /* 2**b: an exhaustive analysis for b = 32 and a partial analysis for */
93 /* b = 48', Math. Comp. 189, pp 331-344, 1990). */
95 /* 48-bit integers are stored in 4 integer array elements with 12 bits */
96 /* per element. Hence the routine is portable across machines with */
97 /* integers of 32 bits or more. */
99 /* ===================================================================== */
101 /* .. Parameters .. */
103 /* .. Local Scalars .. */
105 /* .. Local Arrays .. */
107 /* .. Intrinsic Functions .. */
109 /* .. Data statements .. */
110 /* Parameter adjustments */
116 /* .. Executable Statements .. */
124 for (i__ = 1; i__ <= i__1; ++i__) {
128 /* Multiply the seed by i-th power of the multiplier modulo 2**48 */
130 it4 = i4 * mm[i__ + 383];
133 it3 = it3 + i3 * mm[i__ + 383] + i4 * mm[i__ + 255];
136 it2 = it2 + i2 * mm[i__ + 383] + i3 * mm[i__ + 255] + i4 * mm[i__ +
140 it1 = it1 + i1 * mm[i__ + 383] + i2 * mm[i__ + 255] + i3 * mm[i__ +
141 127] + i4 * mm[i__ - 1];
144 /* Convert 48-bit integer to a real number in the interval (0,1) */
146 x[i__] = ((doublereal) it1 + ((doublereal) it2 + ((doublereal) it3 + (
147 doublereal) it4 * 2.44140625e-4) * 2.44140625e-4) *
148 2.44140625e-4) * 2.44140625e-4;
151 /* If a real number has n bits of precision, and the first */
152 /* n bits of the 48-bit integer above happen to be all 1 (which */
153 /* will occur about once every 2**n calls), then X( I ) will */
154 /* be rounded to exactly 1.0. */
155 /* Since X( I ) is not supposed to return exactly 0.0 or 1.0, */
156 /* the statistically correct thing to do in this situation is */
157 /* simply to iterate again. */
158 /* N.B. the case X( I ) = 0.0 should not be possible. */
169 /* Return final value of seed */