[SOLVED] x to the power y in bash shell

hoi · 09-02-2013, 04:06 AM

echo "$a^$b" | bc -l
Where 'a' is a floating point and 'b' is integer.
If 'a' and 'b' are both floating point then above command does not work.
How to do when 'a' and 'b' both are floating point?

basica · 09-02-2013, 04:13 AM

Google brought up this wikipedia entry, seems like writing a function can take care of this in bc.

Berhanie · 09-02-2013, 04:28 AM

right, you can use "bc -l" and the fact that a ^ b = exp(b * log(a)). that's also mentioned in the link above.
example (computes the square root of 25):

Code:

echo "e(0.5 * l(25))" | bc -l

eklavya · 09-02-2013, 04:42 AM

well if you want to use awk, you can use

Code:

echo "" | awk 'END {print "'${a}'" ^ "'${b}'" }'

So script will look like this.

Code:

#!/bin/bash
a=4.2
b=3.5
echo "" | awk 'END {print "'${a}'" ^ "'${b}'" }'

When you will run this, the output will be
151.835

hoi · 09-02-2013, 04:53 AM

Thanks to all for quick response....