Description

Functions are Scilab procedures ("macro", "function" and "procedure" have the save meaning).

Function definition

Usually, they are defined in files with an editor and loaded into Scilab by getf or through a library (see lib or genlib). But They can also be defined on-line (see deff or function o. A function is defined by two components:

 function [y1,...,yn]=foo(x1,...,xm)
 function [y1,...,yn,varargout]=foo(x1,...,xm,varargin)
   
        

The "syntax definition" line gives the "full" calling syntax of this function. The yi are output variables calculated as functions of input variables xi and variables existing in Scilab when the function is executed.

Calling function

Usually function calling syntax is [y1,...,yn]=foo(x1,...,xm). Shorter input or output argument list than definition ones may be used. In such cases, only the first variables from the left are used of set. The argn function may be used to get the actual number of calling arguments.

It is also possible to use "named argument" to specify input arguments: suppose function fun1 defined as function y1=fun1(x1,x2,x3) then it call be called with a syntax like y=fun1(x1=33,x3=[1 2 3]) within fun1 x2 will be undefined. It is possible to check for defined variables with the exists function

When a function has no left hand side argument and is called only with character string arguments, the callling syntax may be simplified fun('a','toto','a string') can be replaced by fun a toto 'a string'

Miscellaneous

Functions are Scilab objects (with type numbers 13 or 11). They and can be manipulated (built, saved, loaded, passed as arguments,..) as other variable types.

Collections of functions can be collected in libraries. Functions which begin with % sign (e.g. %foo) are often used to overload (see overloading) operations or functions for new data type.

Examples

//inline definition (see function)
function [x,y]=myfct(a,b)
x=a+b
y=a-b
endfunction

[x,y]=myfct(3,2)

//inline definition (see deff)
deff('[x,y]=myfct(a,b)',['x=a+b';
                         'y=a-b'])
// definition in an ascii file (see exec)
exec SCI/macros/elem/asin.sci;

// definition in an ascii file (see getf)
getf SCI/macros/elem/asin.sci;

 
  

See also