# Float Precision

**URL:** <https://discourse.processing.org/t/float-precision/13836>\
**Category:** Beginners\
**Created:** [September 6, 2019, 3:56am UTC](https://discourse.processing.org/t/float-precision/13836 "2019-09-06T03:56:14Z")\
**Posts on this page:** 16\
**Page:** 1

<div class="post-metadata">

**Author:** ![grumo](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/grumo/32/604_2.png) [@grumo](https://discourse.processing.org/u/grumo)\
**Post date:** [September 6, 2019, 3:56am UTC](https://discourse.processing.org/t/float-precision/13836/1 "2019-09-06T03:56:14Z")

</div>

I’m using doubles for some mathematical calculations and I’m getting these two values:

a = -69.49068165087722  
n = 304.2372372266157

The problem is when I do this:

```auto
float fa = (float) a;
float fb = (float) b;

```

I get:  
fa: -69.490685  
fb: 304.23724

Losing a lot of the precision. Of course, this was expected but floats can’t reach at least 8 decimals? I can use six (like the fa variable in this example) but I also don’t know why the second value have even less decimal positions. How can I achieve floats of six decimals in both cases?

Thanks for any help, this is nuts.

---

<div class="post-metadata">

**Author:** ![kll](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/kll/32/964_2.png) [@kll](https://discourse.processing.org/u/kll)\
**Post date:** [September 6, 2019, 3:59am UTC](https://discourse.processing.org/t/float-precision/13836/2 "2019-09-06T03:59:24Z")

</div>

> [@grumo](#):
>
> I’m using doubles  
> a = -69.49068165087722

```auto
a = -69.49068165087722d;

```

would be double

---

<div class="post-metadata">

**Author:** ![grumo](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/grumo/32/604_2.png) [@grumo](https://discourse.processing.org/u/grumo)\
**Post date:** [September 6, 2019, 4:02am UTC](https://discourse.processing.org/t/float-precision/13836/3 "2019-09-06T04:02:59Z")

</div>

Thanks for your message. The thing is that I need to use floats (to send the values over OSC). How can I convert these doubles to floats but keeping at least 6 decimal positions?

---

<div class="post-metadata">

**Author:** ![kll](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/kll/32/964_2.png) [@kll](https://discourse.processing.org/u/kll)\
**Post date:** [September 6, 2019, 4:19am UTC](https://discourse.processing.org/t/float-precision/13836/4 "2019-09-06T04:19:36Z")

</div>

```auto
float af =2;
float bf =3;
float resultf,resultffromd;
double ad=2d;
double bd=3d;
double resultd;

resultf = af/bf;
resultd = ad/bd;
resultffromd = (float)(resultd);

println("float min: "+Float.MIN_VALUE+ "\t\t max: "+Float.MAX_VALUE);
println("double min: "+Double.MIN_VALUE+ "\t\t max: "+Double.MAX_VALUE);

println("resultf "+resultf);
println("resultd "+resultd);
println("resultffromd "+resultffromd);

```

shows

```auto
float min: 1.4E-45 max: 3.4028235E38
double min: 4.9E-324 max: 1.7976931348623157E308
resultf 0.6666667
resultd 0.6666666666666666
resultffromd 0.6666667

```

so for float i see 7 decimales?

* * *

please show usable code here to verify your problem

---

<div class="post-metadata">

**Author:** ![grumo](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/grumo/32/604_2.png) [@grumo](https://discourse.processing.org/u/grumo)\
**Post date:** [September 6, 2019, 4:26am UTC](https://discourse.processing.org/t/float-precision/13836/5 "2019-09-06T04:26:21Z")

</div>

If you run this code with one of the double values from my calculations:

```auto
double resultd;
float resultffromd;

resultd = -75.36681540070782;
resultffromd = (float)(resultd);

println("resultd "+resultd);
println("resultffromd "+resultffromd);

```

You get:  
resultd -75.36681365966797  
resultffromd -75.36681

resultfromd have just five decimal positions. I would need six and I don’t know why in the conversion from double to float I’m losing one. Maybe it has to do that is a negative number?

---

<div class="post-metadata">

**Author:** ![kll](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/kll/32/964_2.png) [@kll](https://discourse.processing.org/u/kll)\
**Post date:** [September 6, 2019, 4:28am UTC](https://discourse.processing.org/t/float-precision/13836/6 "2019-09-06T04:28:29Z")

</div>

your code not run here??

> resultd cannot be resolved to a variable

---

<div class="post-metadata">

**Author:** ![grumo](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/grumo/32/604_2.png) [@grumo](https://discourse.processing.org/u/grumo)\
**Post date:** [September 6, 2019, 4:28am UTC](https://discourse.processing.org/t/float-precision/13836/7 "2019-09-06T04:28:47Z")

</div>

Actually, sometimes I get six decimal values. When the integer part of the number have three positions then my decimal count goes down again (i.e.: 322.91475198111 goes 322.915 --losing three decimal positions from six possibles)

---

<div class="post-metadata">

**Author:** ![grumo](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/grumo/32/604_2.png) [@grumo](https://discourse.processing.org/u/grumo)\
**Post date:** [September 6, 2019, 4:30am UTC](https://discourse.processing.org/t/float-precision/13836/8 "2019-09-06T04:30:58Z")

</div>

I fixed the snippet. try again.

---

<div class="post-metadata">

**Author:** ![kll](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/kll/32/964_2.png) [@kll](https://discourse.processing.org/u/kll)\
**Post date:** [September 6, 2019, 4:37am UTC](https://discourse.processing.org/t/float-precision/13836/9 "2019-09-06T04:37:06Z")

</div>

thanks, i see that now,  
and it makes no difference if i use  
`75.36681540070782d;`  
so change the sign or the ‘d’ not help.  
and `float(double);` even gives error

* * *

but

```auto
println( (float)(2d/3d) );

```

works!

* * *

what i see is:

```auto
double resultd = -75.36681540070782; // gives -75.36681
double resultd = -5.36681540070782; // gives -5.3668156

```

and see for a 4 byte float  
[https://en.wikipedia.org/wiki/Single-precision\_floating-point\_format](https://en.wikipedia.org/wiki/Single-precision_floating-point_format) ,

---

<div class="post-metadata">

**Author:** ![jeremydouglass](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/jeremydouglass/32/20_2.png) [@jeremydouglass](https://discourse.processing.org/u/jeremydouglass)\
**Post date:** [September 6, 2019, 4:57am UTC](https://discourse.processing.org/t/float-precision/13836/10 "2019-09-06T04:57:54Z")

</div>

> [@grumo](#):
>
> I need to use floats (to send the values over OSC)

You might find some ideas in this previous discussion helpful:

> [@oscP5 library, oscEvent\_checkTypetag](https://discourse.processing.org/t/oscp5-library-oscevent-checktypetag/3229):
>
> Hello, i am working on program about sending/receiving messages with oscP5 library…My problem is that in the begging i have declare my values as double but into the oscEvent(OscMessage m) i dont know how can i check if the packages containing double values… I know that the function for this job is if (m.checkTypetag(“fff”)) but for float values. Which one that i must put in the parenthesis represent double values? Thank you

If you need precision, you could still send your data over OSC – as double directly if it is supported, or with type conversion – depending on your speed / bandwidth needs, even sending your double as a string, for example.

I don’t think that Java floating point has fixed decimal precision – the precision depends on the values. Not sure that explains your issue entirely, but it sounds like floats are not the way to go in your case. Instead, maybe work around the OSC bottleneck…

> [@oscP5 library, oscEvent\_checkTypetag](https://discourse.processing.org/t/oscp5-library-oscevent-checktypetag/3229/6):
>
> If you search the oscp5 source for “double”, there are many hits throughout the code for sending and receiving doubles and interpreting double tags. It appears that the oscp5 library for Processing has full double support (untested). For example:

---

<div class="post-metadata">

**Author:** ![GoToLoop](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/gotoloop/32/86_2.png) [@GoToLoop](https://discourse.processing.org/u/GoToLoop)\
**Post date:** [September 6, 2019, 9:10am UTC](https://discourse.processing.org/t/float-precision/13836/11 "2019-09-06T09:10:07Z")

</div>

> [@Is it possible higher precision than double?](https://discourse.processing.org/t/is-it-possible-higher-precision-than-double/13764/4):
>
> Make sure to use constants & methods from Math class only and all non-integer numerical literals are suffixed w/ d: warning[Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Math.html](http://Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Math.html) TAU → 2 \* Math.PI cos(PI) → Math.cos(Math.PI) -5.4 → -5.4d 1e3 → 1e3d

---

<div class="post-metadata">

**Author:** ![kll](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/kll/32/964_2.png) [@kll](https://discourse.processing.org/u/kll)\
**Post date:** [September 6, 2019, 9:38am UTC](https://discourse.processing.org/t/float-precision/13836/12 "2019-09-06T09:38:21Z")

</div>

```auto
double d = -75.36681540070782d;
float f = (float)(d);
int i = (int)(d);

float sendf = (float)( d - (double)(i) ); 
println(" d "+d+" f "+f+" i "+i);

println(" a hack could be to send 2 numbers: one integer "+i+" and a better float for the decimals only "+sendf); 

double gotd = (double)(i) + (double)(sendf);
println(" on the other side combine it again: "+gotd);

```

see

```auto
 d -75.36681540070782 f -75.36681 i -75
 a hack could be to send 2 numbers: 
one integer -75 and 
a better float for the decimals only -0.3668154
 on the other side combine it again: -75.36681538820267

```

---

<div class="post-metadata">

**Author:** ![markcosmic](https://avatars.discourse-cdn.com/v4/letter/m/ecc23a/32.png) [@markcosmic](https://discourse.processing.org/u/markcosmic)\
**Post date:** [September 6, 2019, 7:06pm UTC](https://discourse.processing.org/t/float-precision/13836/13 "2019-09-06T19:06:21Z")

</div>

Here’s an untested thought for you. Maybe try using the nf() function on your double, which creates a string, then convert it back to a number. I haven’t tested it but it may work using less code.

---

<div class="post-metadata">

**Author:** ![markcosmic](https://avatars.discourse-cdn.com/v4/letter/m/ecc23a/32.png) [@markcosmic](https://discourse.processing.org/u/markcosmic)\
**Post date:** [September 6, 2019, 7:52pm UTC](https://discourse.processing.org/t/float-precision/13836/14 "2019-09-06T19:52:52Z")

</div>

Ok. I tested it. It worked. Try this example:  
double d1,d2;

void setup() {  
size(screen.width, screen.height);  
d1 = 37.123456789090909  
d2 = -371.123456789090909  
println(d1 + " " + d2);  
String dd1 = nf(d1,4,6);  
String dd2 = nf(d2,4,6);  
println(float(dd1)+" "+float(dd2));  
}

void draw() {  
background(0,0,255);  
}

---

<div class="post-metadata">

**Author:** ![kll](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/kll/32/964_2.png) [@kll](https://discourse.processing.org/u/kll)\
**Post date:** [September 7, 2019, 1:09am UTC](https://discourse.processing.org/t/float-precision/13836/15 "2019-09-07T01:09:01Z")

</div>

very good, send a string is a valid idea  
if there are no concerns about time / bandwidth

 ![doubleasstring](https://canada1.discourse-cdn.com/flex036/uploads/processingfoundation1/original/2X/0/0ed3c56ed5533131634cb412faa1585b839cc534.png)

---

<div class="post-metadata">

**Author:** ![jeremydouglass](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/jeremydouglass/32/20_2.png) [@jeremydouglass](https://discourse.processing.org/u/jeremydouglass)\
**Post date:** [September 7, 2019, 4:10am UTC](https://discourse.processing.org/t/float-precision/13836/16 "2019-09-07T04:10:43Z")

</div>

These things are all great workarounds in general cases. But if the goal is “I have doubles, and want to send them over OSC, _so they have to become floats_”… then no, they don’t have to become floats.

Just send OSC doubles. Problem solved.

```auto
import oscP5.*;
import netP5.*;
OscP5 oscP5;
NetAddress myRemoteLocation;

void setup() {
  size(400,400);
  frameRate(25);
  oscP5 = new OscP5(this,12000);
  myRemoteLocation = new NetAddress("127.0.0.1",12000);
}

void draw(){
  background(0);
}

void mousePressed() {
  OscMessage myMessage = new OscMessage("/test");
  double d = 3.1415926535897932384626433832795028841971693993751;
  // 50 digits -- more than will fit in a double
  d += (int)random(100,900);
  // it will store about n.1415927410126 or so
  // w decimal matching up to n.141592
  double a = -69.49068165087722;
  double n = 304.2372372266157;
  myMessage.add(d);
  myMessage.add(a);  
  myMessage.add(n);
  oscP5.send(myMessage, myRemoteLocation); 
}

void oscEvent(OscMessage theOscMessage) {
  // double math on the receiving end
  print(millis(), "received", theOscMessage.typetag(), ": ");
  double d = theOscMessage.get(0).doubleValue();
  double a = theOscMessage.get(1).doubleValue();
  double n = theOscMessage.get(2).doubleValue();
  println(d, a, n);
  // prints ~12 decimals of precision, xxx.141592741012xx
}

```

> 6818 received ddd : 147.14159274101257 -69.49068450927734 304.23724365234375  
> 7930 received ddd : 494.1415927410126 -69.49068450927734 304.23724365234375  
> 8851 received ddd : 345.1415927410126 -69.49068450927734 304.23724365234375