# Value NaN of a variable
**URL:** https://discourse.processing.org/t/value-nan-of-a-variable/14220
**Category:** Beginners
**Created:** [September 26, 2019, 4:01pm UTC](https://discourse.processing.org/t/value-nan-of-a-variable/14220 "2019-09-26T16:01:06Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@Ignaki](https://discourse.processing.org/u/Ignaki)
#### Post date: [September 26, 2019, 4:01pm UTC](https://discourse.processing.org/t/value-nan-of-a-variable/14220/1 "2019-09-26T16:01:06Z")
What does it mean wnen the printed value of a variable is “NaN”?
---
### Author:  [@kll](https://discourse.processing.org/u/kll)
#### Post date: [September 26, 2019, 5:19pm UTC](https://discourse.processing.org/t/value-nan-of-a-variable/14220/2 "2019-09-26T17:19:59Z")
> `NaN` means _“Not a Number”_
```auto
println(0.0/0.0);
println(sqrt(-1));
```
why not show the code what produces it?
---
### Author:  [@quark](https://discourse.processing.org/u/quark)
#### Post date: [September 26, 2019, 6:28pm UTC](https://discourse.processing.org/t/value-nan-of-a-variable/14220/3 "2019-09-26T18:28:11Z")
Lets assume you are talking about a `float`. In Java a `float` is stored in 4 bytes of memory that’s 32 bits, since each bit can be 0 or 1 that gives us 4294967296 different combinations to encode a floating point number. Not all those combinations represent a valid floating point number hence **Not a Number** or `NaN`
---
### Author:  [@Ignaki](https://discourse.processing.org/u/Ignaki)
#### Post date: [September 30, 2019, 6:57pm UTC](https://discourse.processing.org/t/value-nan-of-a-variable/14220/4 "2019-09-30T18:57:05Z")
Hi, this is the code that produces NaN:
```auto
void setup()
{
size(1000,1000);
background(255);
}
void draw()
{
float x,y,xm,xM,ym,yM,A,B,inc,Zx,Zy;
xm = -10; xM = 10; ym = -10; yM = 10;
inc = (xM-xm)/1000;
x = xm; y = ym;
A = (x - xm)/(xM-xm)*1000;
B = (y-ym)/(yM-ym)*1000;
println(x,y,inc);
for (int i = 0; i < 1000; i=i+1)
{
for (int k = 0; k < 1000; k++)
{
for (int l = 0; l < 20 ; l++)
{ println(x,y);
Zx = x*x-y*y;
Zy = 2*x*y;
if( Zx*Zx + Zy*Zy < 10)
{A = (x - xm)/(xM-xm)*1000;
B = (y-ym)/(yM-ym)*1000;
stroke(l);
point(A,B);
}
x = Zx;
y = Zy;
}
y = ym + k*inc;
}
x = xm + i*inc;
}
exit();
}
```
---
### Author:  [@kll](https://discourse.processing.org/u/kll)
#### Post date: [September 30, 2019, 7:38pm UTC](https://discourse.processing.org/t/value-nan-of-a-variable/14220/5 "2019-09-30T19:38:25Z")
that code must be posted in the
` Preformatted text ` from the editor menu
> Zx = xx-yy;
> Zy = 2xy;
this code can not run.
BUT
should it mean:
```auto
Zx = x*x-y*y;
Zy = 2*x*y;
```
the code runs and produce your NaN error.
* * *
try
```auto
println( "float min: "+Float.MIN_VALUE+ " max: "+Float.MAX_VALUE);
```
that tells you the range of possible FLOAT numbers
your loops do
`x = Zx = x*x-y*y;`
after 7 loops that value is out of range…
* * *
and the position you calculate for the points
`point(A,B);`
is always 0 , 0
* * *
sorry but to run that math 20 000 000 times ( points ) is questionable
---
### Author:  [@Ignaki](https://discourse.processing.org/u/Ignaki)
#### Post date: [October 1, 2019, 3:31pm UTC](https://discourse.processing.org/t/value-nan-of-a-variable/14220/6 "2019-10-01T15:31:17Z")
Thank you very much.
It’s obvious that I have some serious misconceptions, is there any book that explains in comprehensvly processing functioning?
---
### Author:  [@kll](https://discourse.processing.org/u/kll)
#### Post date: [October 2, 2019, 12:56am UTC](https://discourse.processing.org/t/value-nan-of-a-variable/14220/7 "2019-10-02T00:56:36Z")
please repair your above code posting first.
* * *
i asked you to try one line of code to understand the floating point number range
what was the result?
is there a number type that can cover a bigger number range? YES “double”
would it help in your case / math ? i think NOT
* * *
yes there are books,
but also
- the reference [https://processing.org/reference/](https://processing.org/reference/)
- the examples [https://processing.org/examples/](https://processing.org/examples/)
++PDE / File / Examples /…
- add loadable examples
++PDE / Tools / Add Tool / Examples /
- the tutorials [https://processing.org/tutorials/](https://processing.org/tutorials/)
- the videos [http://learningprocessing.com/videos/](http://learningprocessing.com/videos/)
all might depend of YOUR best way of learning.
* * *
the problem is that from you code it is not clear
what you want to do?
- -1- cover the canvas with points and find some nice way to color them?
- -2- use 20 000 000 points to draw some structure on the canvas ?spiral?..
so for -1-:
show a easy start:
```auto
void setup() {
size(500, 500);
colorMode(HSB, width, 100, 100);
}
void draw() {
many_points();
}
void many_points() {
for ( int x = 0; x < width; x++)
for ( int y = 0; y < height; y++ ) {
stroke(x, 100, 100);
point(x, y);
}
}
```
---
### Author:  [@Ignaki](https://discourse.processing.org/u/Ignaki)
#### Post date: [October 3, 2019, 3:34pm UTC](https://discourse.processing.org/t/value-nan-of-a-variable/14220/8 "2019-10-03T15:34:07Z")
Again, thank you very much!!!