bc is ignoring scale option

linux bash bc
dabest1 picture dabest1 · Dec 20, 2012 · Viewed 32.4k times · Source

I can't figure out why bc tool sometimes ignores the scale option.

Here is an example:

> echo 'scale=2; 2.777 - 1.4744' | bc
1.3026

Expected result is:

1.30

Additional information:

> bash --version
GNU bash, version 2.05b.0(1)-release (x86_64-suse-linux)
Copyright (C) 2002 Free Software Foundation, Inc.
> bc --version
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.

Answer

Kent picture Kent · Dec 20, 2012

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.

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