proc#

Purpose#

Begins the definition of a multi-line recursive procedure. Procedures are user-defined functions with local or global variables.

Format#

proc (nrets) = name(arglist);
proc name(arglist);

Parameters

nrets:

(constant) number of objects returned by the procedure. If nrets is not explicitly given, the default is 1. Legal values are 0 to 1023. The retp statement is used to return values from a procedure.

name:

(literal) name of the procedure. This name will be a global symbol.

arglist:

a list of names, separated by commas, to be used inside the procedure to refer to the arguments that are passed to the procedure when the procedure is called. These will always be local to the procedure, and cannot be accessed from outside the procedure or from other procedures.

Remarks#

A procedure definition begins with the proc statement and ends with the endp statement.

An example of a procedure definition is:

proc dog(x, y, z); /* procedure declaration */
local a, b;        /* local variable declarations */
   a = x .* x;
   b = y .* y;
   a = a ./ x;
   b = b ./ y;
   z = z .* z;
   z = inv(z);
   retp(a'b*z);  /* return with value of a'b*z */
endp;             /* end of procedure definition */

Procedures can be used just as if they were functions intrinsic to the language. Below are the possible variations depending on the number of items the procedure returns.

Returns 1 item:

y = dog(i, j, k);

Returns multiple items:

{ x, y, z } = cat(i, j, k);

Returns no items:

fish(i, j, k);

If the procedure does not return any items or you want to discard the returned items:

call dog(i, j, k);

Procedure definitions may not be nested.

For more details on writing procedures, see Procedures and Keywords,