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math.random() doesn't return anything useful when lua_Number is int. I
think it makes sense for at least the one and two argument versions to
return something useful, and the attached patch attempts to do this.

-- 
gram
diff -Naur lua-5.0.2.orig/src/lib/lmathlib.c lua-5.0.2/src/lib/lmathlib.c
--- lua-5.0.2.orig/src/lib/lmathlib.c	2003-03-11 06:30:37.000000000 -0600
+++ lua-5.0.2/src/lib/lmathlib.c	2005-08-29 14:00:18.000000000 -0500
@@ -170,23 +170,23 @@
 static int math_random (lua_State *L) {
   /* the `%' avoids the (rare) case of r==1, and is needed also because on
      some systems (SunOS!) `rand()' may return a value larger than RAND_MAX */
-  lua_Number r = (lua_Number)(rand()%RAND_MAX) / (lua_Number)RAND_MAX;
+  int r = rand()%RAND_MAX;
   switch (lua_gettop(L)) {  /* check number of arguments */
     case 0: {  /* no arguments */
-      lua_pushnumber(L, r);  /* Number between 0 and 1 */
+      lua_pushnumber(L, (lua_Number)r / (lua_Number)RAND_MAX);  /* Number between 0 and 1 */
       break;
     }
     case 1: {  /* only upper limit */
       int u = luaL_checkint(L, 1);
       luaL_argcheck(L, 1<=u, 1, "interval is empty");
-      lua_pushnumber(L, (int)floor(r*u)+1);  /* int between 1 and `u' */
+      lua_pushnumber(L, (int)floor(r%u)+1);  /* int between 1 and `u' */
       break;
     }
     case 2: {  /* lower and upper limits */
       int l = luaL_checkint(L, 1);
       int u = luaL_checkint(L, 2);
       luaL_argcheck(L, l<=u, 2, "interval is empty");
-      lua_pushnumber(L, (int)floor(r*(u-l+1))+l);  /* int between `l' and `u' */
+      lua_pushnumber(L, (int)floor(r%(u-l+1))+l);  /* int between `l' and `u' */
       break;
     }
     default: return luaL_error(L, "wrong number of arguments");