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       icalc - interactive calculator


       icalc [ file ]


       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 ’?’

            ? 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

       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

       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).


       Greg Ward


       ev(1), rcalc(1), tabfunc(1)