scale = 20 It sets the number of decimal places. $ bc bc 1.06 Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc. This is free software with ABSOLUTELY NO WARRANTY. For details type `warranty’. 355/113 3 scale=20 355/113 3.14159292035398230088 quit $
as Carl pointed out, if you check man page, you can find that line. it is about expression explanations. subtraction won’t read scale variable. If you want to get the expected result (1.30), you could: kent$ echo ‘scale=2; (2.777 – 1.4744)/1’ | bc 1.30 / operation will read scale variable.
Invoke bc with the -l option (to enable the math library) like so: $ echo ‘l(100)/l(10)’ | bc -l 2.00000000000000000000 Use the l function which is the natural log. Take the natural log of the number you are interested in then divide it by the natural log of 10.
Unfortunately, bc doesn’t support scientific notation. However, it can be translated into a format that bc can handle, using extended regex as per POSIX in sed: sed -E ‘s/([+-]?[0-9.]+)[eE]\+?(-?)([0-9]+)/(\1*10^\2\3)/g’ <<<“$value” you can replace the “e” (or “e+”, if the exponent is positive) with “*10^”, which bc will promptly understand. This works even if the exponent … Read more
Just double-quote (“) the expression: echo “$a / ( $b – 34 )” | bc -l Then bash will expand the $ variables and ignore everything else and bc will see an expression with parentheses: $ a=22 $ b=7 $ echo “$a / ( $b – 34 )” 22 / ( 7 – 34 ) … Read more
You can also resort to awk to format: echo “0.1 + 0.1” | bc | awk ‘{printf “%f”, $0}’ or with awk itself doing the math: echo “0.1 0.1” | awk ‘{printf “%f”, $1 + $2}’