1 /* 2 char id_rand[] = "@(#)rand_.c 1.1"; 3 * 4 * Routines to return random values 5 * 6 * calling sequence: 7 * double precision d, drand 8 * i = irand(iflag) 9 * x = rand(iflag) 10 * d = drand(iflag) 11 * where: 12 * If arg is 1, generator is restarted. If arg is 0, next value 13 * is returned. Any other arg is a new seed for the generator. 14 * Integer values will range from 0 thru 2147483647. 15 * Real values will range from 0.0 thru 1.0 16 * (see rand(3)) 17 */ 18 19 #if vax 20 #define RANDMAX 2147483647 21 #else vax 22 #if pdp11 23 #define RANDMAX 32767 24 #else pdp11 25 UNKNOWN MACHINE! 26 #endif pdp11 27 #endif vax 28 29 long irand_(iarg) 30 long *iarg; 31 { 32 if (*iarg) srand((int)*iarg); 33 #if pdp11 34 return(( ((long)rand()) << 16) | rand()); 35 #else pdp11 36 return( rand() ); 37 #endif pdp11 38 } 39 40 float rand_(iarg) 41 long *iarg; 42 { 43 if (*iarg) srand((int)*iarg); 44 return( (float)(rand())/(float)RANDMAX ); 45 } 46 47 double drand_(iarg) 48 long *iarg; 49 { 50 if (*iarg) srand((int)*iarg); 51 return( (double)(rand())/(double)RANDMAX ); 52 } 53