Singular

4.16.1 proc declaration

Syntax:

[static] proc proc_name [(<parameter_list>)
[<help_string>]
{
     <procedure_body>
}
[example
{
     <sequence_of_commands>
}]

Purpose:

Defines a new function, the proc proc_name. Once loaded in a SINGULAR session, the information provided in the help string will be displayed upon entering help proc_name;, while the example section will be executed upon entering example proc_name;. See Parameter list, Help string, and the example in Procedures in a library.
The help string, the parameter list, and the example section are optional. They are, however, mandatory for the procedures listed in the header of a library. The help string is ignored and no example section is allowed if the procedure is defined interactively, i.e., if it is not loaded from a file by the LIB or load command (see LIB and see load ).
In the body of a library, each procedure not meant to be accessible by users should be declared static. See Procedures in a library.

Example:

proc milnor_number (poly p) { ideal i= std(jacob(p)); int m_nr=vdim(i); if (m_nr<0) { "// not an isolated singularity"; } return(m_nr); // the value of m_nr is returned } ring r1=0,(x,y,z),ds; poly p=x^2+y^2+z^5; milnor_number(p); ==> 4

See LIB; Libraries; apply.