| Differences between IDL's floats and Java's floats - a problem [message #36952] |
Thu, 13 November 2003 04:09 |
necr
Messages: 1
Registered: November 2003
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Junior Member |
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I am currently porting some IDL code across to java, and I've run into
a couple of snags with the different ways IDL and Java deal with
numbers. Most of these I have sorted, with trips to the APIs and a
fair bit of googling. However, there is one I haven't managed to sort
out yet.
IDL and Java appear to load floating point numbers from a file in very
different ways.
In IDL, I can read seperate bytes into memory like so:
myvar=0b & readu, 10, myvar
(where 10 is the filehandle of the open file which is being read).
This will result in an unsigned byte being retrieved.
I could read the byte in with java using a DataInputStream like so:
byte a = input.readUnsignedByte();
(where input is my open DataInputStream).
Both these pieces of code would give the same result if run on the
same byte in a file
To read in a float in idl, I would use:
readu, 10, floatvar
(the floatvar would not previously have been set to anything).
And in java:
float f = input.readFloat();
However, running these two pieces of code will not result in the same
float being given out.
My Example
I read in four bytes from a file, both in IDL and Java. Both systems
give me the results 0, 64, 206, 67.
If I run the float code on these same four bytes though, IDL will give
me 412.50 (the value I want), while Java will give 5.951465E-39 -
clearly not the number I'm looking for!
I have tested this on both a Sun and a Windows machine, and have
received the same results.
So, has anyone got any ideas as to why this is happening? And more
importantly, does anyone know what I can do to get the same float
value being loaded in Java?
Thankyou in advance for any help you can give me.
Neil
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