Bash negative exponention arithmetic expansion

Question

Trying to do

1*2^-2

tried code

echo "$((1 * (1/2**2)))" == 0
printf %.3f "$((1 * (1/2**2)))" == 0.000
also tried echo 1/2 | bc == 0

Problem seems that division operator is only not working maybe its a bug in cygwin Executing code in cygwin bash Help

`bash` arithmetic is integer only. `1/2` is equal to `0`, not `0.5`, in `bash` arithmetic. — M. Nejat Aydin, Jul 28 '22 at 14:30
i have limited tools on remote cygwin environment and tried using bc calculator but it was also producing 0 — Tathastu Pandya, Jul 28 '22 at 14:37
`bc` is not related to `bash` and should work. Try `echo "1/2^2" | bc -l` — M. Nejat Aydin, Jul 28 '22 at 14:37

score 1 · Answer 1 · answered Jul 28 '22 at 15:04

1

If awk is available:

$ awk 'BEGIN { print 1 * (1/2**2), 1* (1/2^2) }'
0.25 0.25

$ awk 'BEGIN { printf "%.3f / %.3f", 1 * (1/2**2), 1* (1/2^2) }'
0.250 / 0.250

answered Jul 28 '22 at 15:04

markp-fuso

score 0 · Answer 2 · answered Jul 28 '22 at 14:39

0

 echo "scale = 2; 1 * 2^-2" | bc

Also bc -l option works as suggested in comment

answered Jul 28 '22 at 14:39

Tathastu Pandya

Yes, `bc -l` sets the scale to a default non-zero value (20 I believe): `echo scale | bc -l` – glenn jackman Jul 28 '22 at 15:50

2 Answers2