It is better to report the exact message instead of a truncated version.
The message you report doesn't seem to apply to your code, but well.
float(byte[]) returns an array of floats, not a single float. So you must write:
float[] f = float(data);

apologies, the full error i get is;

1. The method parseFloat(int) in the type PApplet is not applicable for the arguments (byte[])

I just tried declaring an array of float as you suggested;

1. void receive( byte[] data ) {             // <-- default handler
   
     float[] floatRx  = float(data);
    
     print("float: ");
    
     println(f);
     }

However i still receive the same error message when i attempt to run it.

Mmm, I looked at the sources of Processing and I see something strange... I don't know if that's a bug, but while there are a bunch of parseFloat() methods for various flavors of input, you have to use a parseByte() to processes byte[]. Looks like a forgotten leftover...
float() conversion function uses black magic (pre-processing) to do its job, so it is hard to tell, but I will open a bug just in case.

As a workaround, you can just use: float[] floatRx = parseByte(data);

Awesome that works great, thanks for that.

mikepeslo - is the code above working for you to end up with a single float value?  Is taht what you were after.  I am thining we are trying to do something alomost identical in getting a float value some from other controller via UDP that is in IEE754 format over 4 bytes and then trying to convert to 4 bytes back into the float value?  I tried to code above, but only end up with a flaot[] full of the floated values of the bytes.
For example the float value 4.4627 generates 4 bytes = [119,-50,-114,64].  when I run the code above, I simple get floatRx = [119.0,-50.0,-114.0,64.0].  Am I doing something wrong?

So I found this helpful posting about about this conversion: http://dbaktiar.wordpress.com/2009/06/26/float-and-byte-array-conversion/

Then I created this piece of code that seems to work well.  Note I had to change the order the bytes were iterrated in to get the correct values to display.  I am sure this is a big endian/little endian thing.

public float byteArrayToFloat(byte test[]) {
    int MASK = 0xff;
    int bits = 0;
    int i = 3;
    for (int shifter = 3; shifter >= 0; shifter--) {
    bits |= ((int) test[i] & MASK) << (shifter * 8);
    i--;
    }
    return Float.intBitsToFloat(bits);
} 

Hope this helps.  If there is better / simpler way to do this in Processing, I would love to know.

Hi cadomanis,

Upon closer inspection it appears as though you are correct and that the above code was simply floating the values of the byte. The code you posted does work correctly, however i am unsure if there is a simpler way of achieving the conversion in processing.
thanks for the help.

Hi Cadomanis,

To convert a byte array to a single float value, try the following:

float get4bytesFloat(byte[] data, int offset) {
  String hexint=hex(data[offset+3])+hex(data[offset+2])+hex(data[offset+1])+hex(data[offset]);
  return Float.intBitsToFloat(unhex(hexint));
}

Works every time for me.