Here is a little macro to enhance the restricted groff-arithmetics. It
uses the unix bc-command for arbitrary precision calculations (see the
bc-manpage). Maybe it's easier to use for people (like me) who are not
familiar with pic to use its numerical engine like suggested by Ted:
.de calc
. sy echo -n ".ds *calc " > /tmp/calc; echo "\\$*" | bc -l >> /tmp/calc
. pso cat /tmp/calc; rm /tmp/calc
..
The argument of calc is the expression to be calculated; string *calc
returns the result. groff must be called with -U, because the register
.U is readonly and therefore it is not possible to change between
safe/unsafe-mode inside groff.
Examples:
.calc scale=5; 10^2 \" scale=5: 5 digits right from the decimal point.
.tm \*[*calc] => 100.00000
The second example should yield the same result:
.calc scale=5; e(2*l(10))\" e=exponential function, l=natural logarithm.
.tm \*[*calc] => 99.99898
This result is not exact, since bc /truncates/ (without rounding) the
values of e(2) and l (10) to 5 digits (value of scale).
Joachim
