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new option for function "random": random(a,b) returns a<=x<=b

This commit is contained in:
Roberto Ierusalimschy 1998-12-30 15:22:17 -02:00
parent fe5c41fb8a
commit 05d89b5c05
1 changed files with 15 additions and 9 deletions
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24
lmathlib.c
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@ -1,5 +1,5 @@
/* /*
** $Id: lmathlib.c,v 1.11 1998/09/08 19:25:35 roberto Exp roberto $ ** $Id: lmathlib.c,v 1.12 1998/12/28 13:44:54 roberto Exp roberto $
** Lua standard mathematical library ** Lua standard mathematical library
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -153,16 +153,22 @@ static void math_max (void)
} }
static void math_random (void) static void math_random (void) {
{ /* the '%' is needed because on some systems (SunOS!) "rand()" may
/* the '%' is needed because on some systems (SunOS!) "rand()" may */ return a value bigger than RAND_MAX... */
/* return a value bigger than RAND_MAX... */ double r = (double)(rand()%RAND_MAX) / ((double)RAND_MAX+1.0);
double r = (double)(rand()%RAND_MAX) / (double)RAND_MAX; int l = luaL_opt_int(1, 0);
double l = luaL_opt_number(1, 0);
if (l == 0) if (l == 0)
lua_pushnumber(r); lua_pushnumber(r);
else else {
lua_pushnumber((int)(r*l)+1); int u = luaL_opt_int(2, 0);
if (u == 0) {
u = l;
l = 1;
}
luaL_arg_check(l<=u, 1, "interval is empty");
lua_pushnumber((int)(r*(u-l+1))+l);
}
} }