Expand description
§DEF FN<name>(<argument>[,<argument>...]) = <expression>
§Purpose
Define a custom user function for use in other expressions.
§Remarks
User functions may call other user functions but circular calls will result in a stack overflow.
§Example
10 LET PI=3.14159
20 DEF FNDEG(RADIANS)=RADIANS*180/PI
30 PRINT FNDEG(COS(0.707))
RUN
43.562813