What does it mean wnen the printed value of a variable is “NaN”?

`NaN`

means“Not a Number”

```
println(0.0/0.0);
println(sqrt(-1));
```

why not show the code what produces it?

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`

Hi, this is the code that produces NaN:

```
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();
}
```

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:

```
Zx = x*x-y*y;
Zy = 2*x*y;
```

the code runs and produce your NaN error.

try

```
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

Thank you very much.

It’s obvious that I have some serious misconceptions, is there any book that explains in comprehensvly processing functioning?

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/
- the examples https://processing.org/examples/

++PDE / File / Examples /… - add loadable examples

++PDE / Tools / Add Tool / Examples / - the tutorials https://processing.org/tutorials/
- the 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:

```
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);
}
}
```

Again, thank you very much!!!