Release calc version 2.10.2t30

help/define

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+Function definitions
+
+    Function definitions are introduced by the 'define' keyword.
+    Other than this, the basic structure of a function is like in C.
+    That is, parameters are specified for the function within parenthesis,
+    the function body is introduced by a left brace, variables are
+    declared for the function, statements implementing the function
+    follow, and the function is ended with a right brace.
+
+    There are some subtle differences, however.  The types of parameters
+    and variables are not defined at compile time, but instead are typed
+    at runtime.  Thus there is no definitions needed to distinguish
+    between integers, fractions, complex numbers, matrices, and so on.
+    Thus when declaring parameters for a function, only the name of
+    the parameter is needed.  Thus there are never any declarations
+    between the function parameter list and the body of the function.
+
+    For example, the following function computes a factorial:
+
+	    define factorial(n)
+	    {
+		    local	ans;
+
+		    ans = 1;
+		    while (n > 1)
+			    ans *= n--;
+		    return ans;
+	    }
+
+    If a function is very simple and just returns a value, then the
+    function can be defined in shortened manner by using an equals sign
+    in place of the left brace.  In this case, the function declaration
+    is terminated by a newline character, and its value is the specified
+    expression.  Statements such as 'if' are not allowed.  An optional
+    semicolon ending the expression is allowed.  As an example, the
+    average of two numbers could be defined as:
+
+	    define average(a, b) = (a + b) / 2;
+
+    Functions can be defined which can be very complex.  These can be
+    defined on the command line if desired, but editing of partial
+    functions is not possible past a single line.  If an error is made
+    on a previous line, then the function must be finished (with probable
+    errors) and reentered from the beginning.  Thus for complicated
+    functions, it is best to use an editor to create the function in a
+    file, and then enter the calculator and read in the file containing
+    the definition.
+
+    The parameters of a function can be referenced by name, as in
+    normal C usage, or by using the 'param' function.  This function
+    returns the specified parameter of the function it is in, where
+    the parameters are numbered starting from 1.  The total number
+    of parameters to the function is returned by using 'param(0)'.
+    Using this function allows you to implement varargs-like routines
+    which can handle any number of calling parameters.  For example:
+
+	    define sc()
+	    {
+		    local s, i;
+
+		    s = 0;
+		    for (i = 1; i <= param(0); i++)
+			    s += param(i)^3;
+		    return s;
+	    }
+
+    defines a function which returns the sum of the cubes of all it's
+    parameters.