optimised for m=0

In this case no checking of solution minimality is needed.
This makes a huge difference, like 1000+-fold speedup.

Makefile

@@ -18,7 +18,7 @@
 ## 'make allclean' deletes also *.exe files.
 ##
 CC=gcc
-CFLAGS=-O -g -pg
+CFLAGS=-O -g # -pg
 EXT=.exe
 
 all : oneeq systeq

hb.c

@@ -66,7 +66,7 @@ int hb(eq *e, int **sols, int savesols) /* return number elts in the basis; */
       if (!p[lp].node && lp) /* found a solution */
 	{
 	    ntests++;
-	  if (ismsol(e,sol,sol_t,p_t,mark_t)) 
+	  if (e->m==0 || ismsol(e,sol,sol_t,p_t,mark_t)) 
 	    saves(savesols, &solmax, lsol, ++nsol, sol, sols);
 	  goto getnext;
 	}
@@ -84,7 +84,7 @@ int hb(eq *e, int **sols, int savesols) /* return number elts in the basis; */
 	      p[lp+1].node=p[lp].node+sign*x[w];
 	      mark[p[++lp].node]=1;
 	      ntests++;
-	      if (!ismsol(e,sol,sol_t,p_t,mark_t)) goto getnext;
+	      if (e->m>0 && !ismsol(e,sol,sol_t,p_t,mark_t)) goto getnext;
 	    }
 	  else 
 	  getnext:
@@ -106,7 +106,7 @@ int hb(eq *e, int **sols, int savesols) /* return number elts in the basis; */
 		      p[lp].node=p[lp-1].node+sign*x[w];
 		      mark[p[lp].node]=1;
 		      ntests++;
-		      if (!ismsol(e,sol,sol_t,p_t,mark_t)) goto getnext;
+		      if (e->m>0 && !ismsol(e,sol,sol_t,p_t,mark_t)) goto getnext;
 		      goto cont;
 		    }
 		  else 

p39

@@ -1,6 +1,6 @@
-1
+3
 1
 37
 0
 37
-1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 35 37
+1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37