CALC:  Simple calculator program.

The calc program computes the value of an arithmetic expression, and
prints it on standard output.  Although this program may be useful, it
was mostly written as a test of the formula module (see formula.doc).


    calc { var=formula } formula

The value of the final formula is computed and printed.  This formula
may contain references to variables that were assigned values in the
earlier arguments.  These assignments are performed in order; the
formulas they contain may reference variables that were assigned
values earlier.  A variable name may be a single lower-case letter, or
a lower-case letter followed by a single digit.

For the syntax of formulas, see formula.doc.

Some examples:

   > calc "3+5"

   > calc "p=0.913" "100p(1-p)"

   > calc "x1=8.9E5" "x2=1.2E6" "Sqrt(x1*x2)"

   > calc "x=4.8" "y=x+1.9" "z=y-3.1" "Exp { - (x^2+y^2+z^2) / 2 }"

   > calc "s=3" "i=2" "n=10" "sin(4)"

   Note that "sin(4)" is interpreted as "s*i*n*(4)"!
   "Sin(4)" would evaluate the sine of 4.

   > calc "1.3e4+12.1"
   Undefined variable: e4
   You have to use upper-case "E" for numbers in scientific notation.