32bit floating point representation

[stupidchief]

Hi,
How would you represent the following number in
32bit binary?

-7 x 2^-87

A brief explanation would be helpful.
I understand the basics i.e. first bit is sign bit - next 8 are biased exponent etc..

[OneOffDriveByPoster]

stupidchief @ Sat Sep 20, 2008 8:38 am wrote:

Hi,
How would you represent the following number in
32bit binary?

-7 x 2^-87

A brief explanation would be helpful.
I understand the basics i.e. first bit is sign bit - next 8 are biased exponent etc..

Just one example... then

7 in binary:
111

Normalize:
7 = 1.11b * 2^+2

So, exponent field is:
-87 + 2 + 127 = 42 = 00101010b

Your float:
1 001 0101 0 110...
or hex 95 60 00 00

[stupidchief]

Thanks a lot.
The -7 was confusing me.
wasn't sure if you were supposed to use a 2's complement
binary version of -7