NAME
icalc - interactive calculator
SYNOPSIS
icalc [ file ]
DESCRIPTION
Icalc is a algebraic calculator designed primarily for interactive use.
Each formula definition file is read and compiled. The standard input
is then read, expressions are evaluated and results are sent to the
standard output. If a newline is escaped using a backslash, input is
continued on the next line.
An expression contains real numbers, variable names, function calls,
and the following operators:
+ - * / ^
Operators are evaluated left to right, except ’^’, which is right
associative. Exponentiation has the highest precedence; multiplication
and division are evaluated before addition and subtraction.
Expressions can be grouped with parentheses. Each result is assigned a
number, which can be used in future expressions. For example, the
expression ($3*10) is the result of the third calculation multiplied by
ten. A dollar sign by itself may be used for the previous result. All
values are double precision real.
In addition, variables and functions can be defined by the user. A
variable definition has the form:
var = expression ;
Any instance of the variable in an expression will be replaced with its
definition. A function definition has the form:
func(a1, a2, ..) = expression ;
The expression can contain instances of the function arguments as well
as other variables and functions. Function names can be passed as
arguments. Recursive functions can be defined using calls to the
defined function or other functions calling the defined function.
To define a constant expression, simply replace the equals sign (’=’)
with a colon (’:’) in a definition. Constant expressions are evaluated
only once, the first time they are used. This avoids repeated
evaluation of expressions whose values never change. Ideally, a
constant expression contains only numbers and references to previously
defined constant expressions and functions. Constant function
definitions are are replaced by their value in any expression that uses
them with constant arguments. All predefined functions and variables
have the constant attribute. Thus, "sin(PI/4)" in an expression would
be immediately replaced by ".707108" unless sin() or PI were redefined
by the user. (Note that redefining constant expressions is not a
recommended practice!)
A variable or function’s definition can be displayed with the ’?’
command:
? name
If no name is given, all definitions are printed. The ’>’ command
writes definitions to a file:
> file
Similarly, the ’<’ command loads definitions.
The following library of predefined functions and variables is
provided:
PI the ratio of a circle’s circumference to its diameter.
if(cond, then, else)
if cond is greater than zero, then is evaluated, otherwise
else is evaluated. This function is necessary for recursive
definitions.
select(N, a1, a2, ..)
return aN (N is rounded to the nearest integer). This
function provides array capabilities. If N is zero, the
number of available arguments is returned.
rand(x) compute a random number between 0 and 1 based on x.
floor(x) return largest integer not greater than x.
ceil(x) return smallest integer not less than x.
sqrt(x) return square root of x.
exp(x) compute e to the power of x (e approx = 2.718281828).
log(x) compute the logarithm of x to the base e.
log10(x) compute the logarithm of x to the base 10.
sin(x), cos(x), tan(x)
trigonometric functions.
asin(x), acos(x), atan(x)
inverse trigonometric functions.
atan2(y, x)
inverse tangent of y/x (range -pi to pi).
AUTHOR
Greg Ward
SEE ALSO
ev(1), rcalc(1), tabfunc(1)