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Arithmetic calculations in bash file

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# 1  
Old 03-03-2013
Arithmetic calculations in bash file
I have 2 numbers

Code:
xmin = 0.369000018
xmax = 0.569000006

and want to calculate

Code:
(xmax- xmin) / 5.0

I have tried using $(( )) but is always giving an error
# 2  
Old 03-03-2013
Here is an approach using bc
Code:
#!/bin/bash

xmin=0.369000018
xmax=0.569000006

echo "scale=9; ( $xmax - $xmin ) / 5.0" | bc

# 3  
Old 03-03-2013
Quote:
Originally Posted by kristinu
I have 2 numbers

Code:
xmin = 0.369000018
xmax = 0.569000006

and want to calculate

Code:
(xmax- xmin) / 5.0

I have tried using $(( )) but is always giving an error
The bash shell doesn't perform non-integer arithmetic.
You can do it with a recent (newer than 1988) Korn shell:
Code:
xmin=0.369000018
xmax=0.569000006
printf "%.10f\n" $(( (xmax - xmin) / 5.0))

which produces:
Code:
0.0399999976

# 4  
Old 03-03-2013
Bugger. I'm stuck with bash.

---------- Post updated at 07:53 PM ---------- Previous update was at 07:49 PM ----------

I it possible to write a function to do a calculation using bc?

---------- Post updated at 08:02 PM ---------- Previous update was at 07:53 PM ----------

Seems a solution would be in awk

---------- Post updated at 08:04 PM ---------- Previous update was at 08:02 PM ----------

This did not work

Code:
compute() {

  echo "(0.569000006-0.369000018)/5.0" | awk '{ print $1 }'

}

# 5  
Old 03-03-2013
Code:
awk ' BEGIN { printf "%f\n", (0.569000006-0.369000018) / 5.0 } '

# 6  
Old 03-03-2013
Aney idea what's the problem with this?

Code:
awk -v a=0.569000006 -v b=0.369000018 -v c=5.0 '{res= (a-b)/c; print res;}'

# 7  
Old 03-03-2013
You need a BEGIN block which is executed once before any input is read. In this case BEGIN block runs and program exits:
Code:
awk -v a=0.569000006 -v b=0.369000018 -v c=5.0 ' BEGIN {res= (a-b)/c; print res;}'
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