Re: what calculator do you use?

[Greg Wooledge <wooledg@eeg.ccf.org>]

On Mon, Jul 13, 2020 at 01:41:39PM +0200, Klaus Singvogel wrote:
> rhkramer@gmail.com wrote:
> > 
> > From the command line: bc -l (the -l doesn't something useful (to me) but I 
> > forget what ;-)
> 
> I'm using "bc -l" either.
> 
> "-l" is including the math lib, for functions like exp, sin, cos, etc.

This is correct.  The -l *also* sets the bc "scale" variable to 20,
meaning it calculates non-integer values to 20 decimal places.  Using
such a high precision is extremely important with certain calculations,
where using lower precision values would cause severe rounding errors,
which would accumulate and worsen quite dramatically.

unicorn:~$ echo 'e(1.4*l(500))' | bc -l
6005.62216990715616614180
unicorn:~$ echo 'scale=2; e(1.4*l(500))' | bc -l
5943.18

Never set a low scale value in bc.

If you don't want to see 20 digits after the decimal place, perform
rounding in a separate step.

unicorn:~$ printf '%.2f\n' "$(echo 'e(1.4*l(500))' | bc -l)"
6005.62