.TH CALC 1STAT "March 14, 1981"
.SH NAME
calc \- calculator
.SH SYNOPSIS
.B calc
.SH DESCRIPTION
.I Calc
is a calculator for doing real arithmetic using familiar infix notation.
.I Calc
uses a calculation method based on the popular program VisiCalc
in that it allows variables to be define by equations.
For example,
.ce
A = B + C * D
says that whatever B, C, and D are, A is equal to the above function of them.
If B, C, or D change, then so does the value of A because it depends on them.
(To set A to the value of a function of several variables so that it doesn't
change over time, you prepend a # before the = sign to emphasize you
want the current value.)
In
.I calc,
you get the prompt, "CALC:\ ", and you type in an expression to be calculated.
You can use numbers and even variables.
For example,

.nf
12 + 123/6
a = b^2 + log (sqrt (c))
AVeryLongVariableName = (a+b) - c*d/e ^ f%log (sqrt (exp (abs (x))))
.fi

The usual operators and precedences are available along with the
common mathematical functions.
Parentheses can be used for clarity.
.SH SEE\ ALSO
Calc: A calculator program,
Gary Perlman, Cognitive Science Laboratory.
.SH AUTHOR
Gary Perlman
.SH BUGS
.I Calc
will not allow backward influences caused by a series of expressions like
.in 12
.nf
a = sqrt (b^2 + c^2)
b = sqrt (a^2 + c^2)
.fi
.in
The above says that
.I a
is defined in terms of
.I b
which is defined in terms of
.I a
causing an infinite regress.
Future versions may allow backward influences without blowing up.
