New command 'setseed' with function com_sseed

to set the random number generator

src/frontend/commands.c

@@ -83,6 +83,7 @@
 #include "resource.h"
 #include "diff.h"
 #include "com_strcmp.h"
+#include "ngspice/randnumb.h"
 
 #include "arg.h"
 
@@ -193,6 +194,10 @@ struct comm spcp_coms[] = {
       { 040000, 0, 0, 0 }, E_DEFHMASK, 0, 1,
       NULL,
       "[vecname] : Change default scale of current working plot." } ,
+    { "setseed", com_sseed, FALSE, FALSE,
+      { 04, 0, 0, 0 }, E_DEFHMASK, 0, 1,
+      NULL,
+      "[seed value] : Reset the random number generator with new seed value." } ,
     { "transpose", com_transpose, FALSE, FALSE,
       { 040000, 040000, 040000, 040000 }, E_DEFHMASK, 1, LOTS,
       NULL,
@@ -666,6 +671,10 @@ struct comm nutcp_coms[] = {
       { 040000, 0, 0, 0 }, E_DEFHMASK, 0, 1,
       NULL,
       "[vecname] : Change default scale of current working plot." } ,
+    { "setseed", com_sseed, FALSE, FALSE,
+      { 04, 0, 0, 0 }, E_DEFHMASK, 0, 1,
+      NULL,
+      "[seed value] : Reset the random number generator with new seed value." } ,
     { "transpose", com_transpose, FALSE, FALSE,
       { 040000, 040000, 040000, 040000 }, E_DEFHMASK, 1, LOTS,
       NULL,

src/include/ngspice/randnumb.h

@@ -1,12 +1,17 @@
 #ifndef ngspice_RANDNUMB_H
 #define ngspice_RANDNUMB_H
 
+#include "ngspice/wordlist.h"
+extern void com_sseed(wordlist *wl);
+extern void setseedinfo(void);
+
 /* initialize random number generators */
 extern void initw(void);
 
 extern void checkseed(void);    /* seed random or set by 'set rndseed=value'*/
 extern double drand(void);
 extern double gauss0(void);
+extern double gauss1(void);
 extern int poisson(double);
 extern double exprand(double);
 

src/main.c

@@ -864,8 +864,10 @@ main(int argc, char **argv)
 
     cp_program = ft_sim->simulator;
 
-    srand((unsigned int) getpid());
-    TausSeed();
+    /* initialze random number generator with seed = 1 */
+    int ii = 1;
+    cp_vset("rndseed", CP_NUM, &ii);
+    com_sseed(NULL);
 
     /* --- Process command line options --- */
     for (;;) {

src/maths/misc/randnumb.c

@@ -65,6 +65,7 @@ double CombLCGTaus(void);
 float  CombLCGTaus2(void);
 
 void rgauss(double* py1, double* py2);
+static bool seedinfo = FALSE;
 
 
 /* Check if a seed has been set by the command 'set rndseed=value'
@@ -213,6 +214,23 @@ double gauss0(void)
   }
 }
 
+
+/***  gauss  ***
+to be reproducible, we just use one value per pass */
+double gauss1(void)
+{
+    double fac, r, v1, v2;
+    do {
+        v1 = 2.0 * CombLCGTaus() - 1.0;
+        v2 = 2.0 * CombLCGTaus() - 1.0;
+        r = v1 * v1 + v2 * v2;
+    } while (r >= 1.0);
+    /*    printf("v1 %f, v2 %f\n", v1, v2); */
+    fac = sqrt(-2.0 * log(r) / r);
+    return v2 * fac;
+}
+
+
 /* Polar form of the Box-Muller generator for Gaussian distributed
    random variates.
    Generator will be fed with two uniformly distributed random variates.
@@ -264,3 +282,51 @@ double exprand(double mean)
     expval = -log(CombLCGTaus()) * mean;
     return expval;
 }
+
+
+
+/* seed random number generators immediately
+* command "setseed"
+*   take value of variable rndseed as seed
+* command "setseed <n>"
+*   seed with number <n>
+*/
+void
+com_sseed(wordlist *wl)
+{
+    int newseed;
+
+    if (wl == NULL) {
+        if (!cp_getvar("rndseed", CP_NUM, &newseed)) {
+            newseed = getpid();
+            cp_vset("rndseed", CP_NUM, &newseed);
+        }
+        srand((unsigned int)newseed);
+        TausSeed();
+    }
+    else if ((sscanf(wl->wl_word, " %d ", &newseed) != 1) ||
+        (newseed <= 0) || (newseed > INT_MAX))
+    {
+        fprintf(cp_err,
+            "\nWarning: Cannot use %s as seed!\n"
+            "    Command 'setseed %s' ignored.\n\n",
+            wl->wl_word, wl->wl_word);
+        return;
+    }
+    else {
+        srand((unsigned int)newseed);
+        TausSeed();
+        cp_vset("rndseed", CP_NUM, &newseed);
+    }
+
+    if (seedinfo)
+        printf("\nSeed value for random number generator is set to %d\n", newseed);
+}
+
+
+void
+setseedinfo(void)
+{
+    seedinfo = TRUE;
+}
+

src/sharedspice.c

@@ -648,8 +648,10 @@ ngSpice_Init(SendChar* printfcn, SendStat* statusfcn, ControlledExit* ngspiceexi
     /* program name*/
     cp_program = ft_sim->simulator;
 
-    srand((unsigned int) getpid());
-    TausSeed();
+    /* initialze random number generator with seed = 1 */
+    int ii = 1;
+    cp_vset("rndseed", CP_NUM, &ii);
+    com_sseed(NULL);
 
     /* set a boolean variable to be used in .control sections */
     bool sm = TRUE;
@@ -741,15 +743,7 @@ bot:
         fprintf (cp_out, "SoS %f, seed value: %ld\n", renormalize(), rseed);
     }
 #elif defined (WaGauss)
-    {
-        unsigned int rseed = 66;
-        if (!cp_getvar("rndseed", CP_NUM, &rseed, 0)) {
-            time_t acttime = time(NULL);
-            rseed = (unsigned int) acttime;
-        }
-        srand(rseed);
         initw();
-    }
 #endif
 
 //  com_version(NULL);