[SOLVED] How do I generate a file of random (IEEE-754 single-precision) floats?

How do I generate a file of random (IEEE-754 single-precision) floats?

In a bash script, I want to generate a file containing IEEE-754 single-precision floating point values (i.e not a text file). I want them to have a uniform distribution over some range (which I have as string variables, $min_val and $max_val ; e.g. -100.0 and 200.0 respectively). I don't care that much about the "quality" of randomness, so anything passable to the naked human eye will do; and I don't want NaNs or infinities.

What's a convenient way to do that? I can't just user random characters from /dev/urandom and such.

Notes:

You may assume the minimum and maximum and not subnormal.
Other reasonable assumptions can be made, but please make them explicitly.

Solution

My Perl seems to pack floats into the IEEE-754 format.

You may need to change this for endian-ness:

perl -e '
    ($min,$max,$count) = @ARGV;
    print pack "f*", $min + rand($max-$min) for 1..$count;
' $min $max $count > floatfile

For reference:

perl -e 'print pack "f*", Inf, Nan, -118.625, 0.15625' | od -x

gives, on my machine:

0000000 0000 7f80 0000 ffc0 4000 c2ed 0000 3e20
0000020

"f<*" forces little-endian; "f>*" forces big-endian.