simplify the non vanishing of the 0th coefficient of the random vector in change of order

jerebertho · jerebertho · commit c4f049105f24 · 2026-03-25T23:54:52.000+01:00
diff --git a/src/fglm/fglm_core.c b/src/fglm/fglm_core.c
@@ -1284,10 +1284,7 @@ static inline long initialize_fglm_data(sp_matfglm_t *matrix,
     if(matrix->dense_mat[i]==0)
       nb++;
   }
-  do{
-      data->vecinit[0] = (CF_t)rand() % prime;
-      /* printf ("data->vecinit[0]=%d\n",data->vecinit[0]); */
-  }while(data->vecinit[0] == 0);
+  data->vecinit[0] = 1 + ((CF_t) rand() % (prime-1)); /* random, nonzero */
   for(szmat_t i = 1; i < matrix->ncols; i++){
     data->vecinit[i] = (CF_t)rand() % prime;
   }

Original file line number	Diff line number	Diff line change
`@@ -1284,10 +1284,7 @@ static inline long initialize_fglm_data(sp_matfglm_t *matrix,`
`1284`	`1284`	`if(matrix->dense_mat[i]==0)`
`1285`	`1285`	`nb++;`
`1286`	`1286`	`}`
`1287`		`- do{`
`1288`		`- data->vecinit[0] = (CF_t)rand() % prime;`
`1289`		`- /* printf ("data->vecinit[0]=%d\n",data->vecinit[0]); */`
`1290`		`- }while(data->vecinit[0] == 0);`
	`1287`	`+ data->vecinit[0] = 1 + ((CF_t) rand() % (prime-1)); /* random, nonzero */`
`1291`	`1288`	`for(szmat_t i = 1; i < matrix->ncols; i++){`
`1292`	`1289`	`data->vecinit[i] = (CF_t)rand() % prime;`
`1293`	`1290`	`}`