# Why are the Math functions so insanely slow?

**URL:** https://forum.kirupa.com/t/why-are-the-math-functions-so-insanely-slow/262983
**Category:** flash
**Created:** [June 11, 2008, 4:38pm UTC](https://forum.kirupa.com/t/why-are-the-math-functions-so-insanely-slow/262983 "2008-06-11T16:38:15Z")
**Posts on this page:** 5
**Page:** 1

<div class="post-metadata">

### Author: ![sekasi](https://avatars.discourse-cdn.com/v4/letter/s/5f8ce5/32.png) [@sekasi](https://forum.kirupa.com/u/sekasi)
#### Post date: [June 11, 2008, 4:38pm UTC](https://forum.kirupa.com/t/why-are-the-math-functions-so-insanely-slow/262983/1 "2008-06-11T16:38:15Z")

</div>

```auto

import flash.utils.getTimer;
var n:Number = 1.5;
var st:Number = getTimer();
var test:int;

function divT():void {    
    st = getTimer();
    for(var i:int=0;i<10000000;i++) {
        test = Math.floor(n);
    }
    trace("Time spent calculating with Math.Floor: " +(getTimer()-st)+ " ms");
}

function divB():void {    
    st = getTimer();
    for(var i:int=0;i<10000000;i++) {
        test = int(1.5);
    }
    trace("Time spent calculating with conversion to int: " +(getTimer()-st)+ " ms");
}

divT();
divB();

```

Whereas I see and understand the results, I don’t get why the built in floor function is so incredibly slow compared to int conversion.

Can anyone shed some light on this?

---

<div class="post-metadata">

### Author: ![sekasi](https://avatars.discourse-cdn.com/v4/letter/s/5f8ce5/32.png) [@sekasi](https://forum.kirupa.com/u/sekasi)
#### Post date: [June 11, 2008, 4:41pm UTC](https://forum.kirupa.com/t/why-are-the-math-functions-so-insanely-slow/262983/2 "2008-06-11T16:41:27Z")

</div>

For those that don’t feel like trying it, this is what it traces out for me;

```auto

Time spent calculating with Math.Floor: 721 ms
Time spent calculating with conversion to int: 34 ms

```

---

<div class="post-metadata">

### Author: ![Anogar](https://avatars.discourse-cdn.com/v4/letter/a/ed655f/32.png) [@Anogar](https://forum.kirupa.com/u/Anogar)
#### Post date: [June 11, 2008, 6:02pm UTC](https://forum.kirupa.com/t/why-are-the-math-functions-so-insanely-slow/262983/3 "2008-06-11T18:02:14Z")

</div>

I believe this is the code (it’s not AS, obviously) used for [FONT=“Courier New”]Math.floor()[/FONT]:

```auto

#include "fdlibm.h"

#ifdef __STDC__
static const double really_big = 1.0e300;
#else
static double really_big = 1.0e300;
#endif

#ifdef __STDC__
	double fd_floor(double x)
#else
	double fd_floor(x)
	double x;
#endif
{
        fd_twoints u;
	int i0,i1,j0;
	unsigned i,j;
        u.d = x;
	i0 = __HI(u);
	i1 = __LO(u);
	j0 = ((i0>>20)&0x7ff)-0x3ff;
	if(j0<20) {
	    if(j0<0) { /* raise inexact if x != 0 */
		if(really_big+x>0.0) {/* return 0*sign(x) if |x|<1 */
		    if(i0>=0) {i0=i1=0;} 
		    else if(((i0&0x7fffffff)|i1)!=0)
			{ i0=0xbff00000;i1=0;}
		}
	    } else {
		i = (0x000fffff)>>j0;
		if(((i0&i)|i1)==0) return x; /* x is integral */
		if(really_big+x>0.0) {	/* raise inexact flag */
		    if(i0<0) i0 += (0x00100000)>>j0;
		    i0 &= (~i); i1=0;
		}
	    }
	} else if (j0>51) {
	    if(j0==0x400) return x+x;	/* inf or NaN */
	    else return x; /* x is integral */
	} else {
	    i = ((unsigned)(0xffffffff))>>(j0-20);
	    if((i1&i)==0) return x;	/* x is integral */
	    if(really_big+x>0.0) { /* raise inexact flag */
		if(i0<0) {
		    if(j0==20) i0+=1; 
		    else {
			j = i1+(1<<(52-j0));
			if((int)j<i1) i0 +=1 ; /* got a carry */
			i1=j;
		    }
		}
		i1 &= (~i);
	    }
	}
        u.d = x;
	__HI(u) = i0;
	__LO(u) = i1;
        x = u.d;
	return x;
}

```

With that much manipulation and evaluation it’s no surprise that it takes a while. All the [FONT=“Courier New”]int() [/FONT]function does is return the number before the ‘.’ - that can’t be a very complex function. (Try [FONT=“Courier New”]trace(int(1.999));[/FONT] for example, it still returns ‘1’.)

---

<div class="post-metadata">

### Author: ![sekasi](https://avatars.discourse-cdn.com/v4/letter/s/5f8ce5/32.png) [@sekasi](https://forum.kirupa.com/u/sekasi)
#### Post date: [June 11, 2008, 6:21pm UTC](https://forum.kirupa.com/t/why-are-the-math-functions-so-insanely-slow/262983/4 "2008-06-11T18:21:01Z")

</div>

> [@Anogar;2340875](#):
>
> All the [FONT=Courier New]int()[/FONT]function does is return the number before the ‘.’ - that can’t be a very complex function. (Try [FONT=Courier New]trace(int(1.999));[/FONT]

Well… try trace(Math.floor(1.9999));

😉

---

<div class="post-metadata">

### Author: ![Anogar](https://avatars.discourse-cdn.com/v4/letter/a/ed655f/32.png) [@Anogar](https://forum.kirupa.com/u/Anogar)
#### Post date: [June 11, 2008, 6:23pm UTC](https://forum.kirupa.com/t/why-are-the-math-functions-so-insanely-slow/262983/5 "2008-06-11T18:23:44Z")

</div>

```auto

trace(int(-1.5)); //traces -1
trace(Math.floor(-1.5)); //traces -2

```

🙂