Binary Square Root 2

[buzzp]

I am looking for a detailed explanation of finding the square root of a binary number (16 bit). I have seen it done using decimal numbers (Newtonian method) and some other methods. I would like to implement this in assembly language using rotate commands and an 8bit software multiply. Can anyone help (I know this is from high school - at least the decimal long hand square root is)?

 

[nbucska]

The simplest iterative process I know:

input number
sq = guess

loop:
guess = (number/guess+guess)/2
loop until changes
sqr=guess


<nbucska@pcperipherals DOT com> subj: eng-tips

 

[nbucska]

sorry, delete 2nd line

<nbucska@pcperipherals DOT com> subj: eng-tips

 

[buzzp]

Thanks for the reply. I knew about that one but thought someone may have come up with a quicker method.

 

[nbucska]

perhaps trial & and error would be faster if you only need
integer solution.


<nbucska@pcperipherals DOT com> subj: eng-tips

 

[buzzp]

To make it funner, I will be finding the sqroot of a 32 bit number now instead of 16. Guess its time to write some code and do some experiments. Thanks again.

 

[hacksaw]

you might try quaternion operators popularized by Jack B. Kuipers. often used in games to speed up the graphics whether 8, 32, or 64 bit

 

[melone]

Does this help?

http://www.dattalo.com/technical/theory/sqrt.html

 

[melone]

Or this?

http://www.rism.com/Trig/square.htm

 

[buzzp]

Thanks Melone. That is helpful as well.

 

[scottydoesntknow]

have you tried compiling a small program that does a sqrt() and looking at what the assembler comes up with?

 

[buzzp]

I am programming in assembly. I have not decided on which method to use. Still digesting options.

 

[hdingman]

u want it in assembler, I Google-searched
"successive approximation root assembler" and found

http://www.finesse.demon.co.uk/steven/sqrt.html

which even had the code for several different ASM routines, varying in method and runtime.

Howard