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Old 08-04-2008, 02:41 AM   #1
skuz_ball
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square root of number using sqrt and/or awk


Hi all,

I'm trying to get the square root of a number and have used a couple of methods but neither has worked for me.

First method:

Quote:
sqrt($number)

Second method:

Quote:
awk '{print sqrt($number)}'

I have read somewhere that I must include <math.h> but am not exactly sure of what this is referring to and haven't seen this in any of the example scripts I have looked at. I am trying to write this using korn shell. Any help would be greatly appreciated.
 
Old 08-04-2008, 02:44 AM   #2
Mr. C.
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How about:

echo sqrt "($number)" | bc
 
Old 08-04-2008, 02:58 AM   #3
skuz_ball
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thanks heaps mate!
 
Old 08-04-2008, 03:54 AM   #4
ghostdog74
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Quote:
Originally Posted by skuz_ball View Post
Hi all,

I'm trying to get the square root of a number and have used a couple of methods but neither has worked for me.

First method:




Second method:




I have read somewhere that I must include <math.h> but am not exactly sure of what this is referring to and haven't seen this in any of the example scripts I have looked at. I am trying to write this using korn shell. Any help would be greatly appreciated.
you need BEGIN in you awk script since there's no file input
Code:
awk 'BEGIN{print sqrt(400)}'
# awk 'BEGIN{print 400**0.5}'
next time when it doesn't work, don't just say it doesn't work. Describe any errors or strange phenomena clearly.
 
Old 08-04-2008, 04:18 AM   #5
matthewg42
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The math.h thing is for when you are writing a program in C. If you are using shell script, you will need to use some external program, as most shells do not include a built-in square root command.

bc is probably the best bet here as it is a very small program (so it is quicker to invoke than other programs), and it can give you a lot of precision, or as little as you want.

bc reads from standard input, so you can echo an expression to evaluate like these examples:
Code:
result1=$(echo "3 + 5" | bc -l)
result2=$(echo "sqrt(3)" | bc -l)
 
  


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