deff - on-line definition of function
On-line definition of function (user defined function): the name of the created function is newfunction. text is a sequence of instructions usually set as a vector of character strings.
This command can be used inside a function and the new function can be an input or output of any other function.
Usually, functions are defined in a file and loaded into Scilab by getf
Some time, in particular when you want to use define strings within deff text is rather difficult to write. A more tractable way may be to define your function in a file as usual, to load it into Scilab by getf (without 'c' option) and use sci2exp to get corresponding deff instructions.
deff('[x]=myplus(y,z)','x=y+z') // deff('[x]=mymacro(y,z)',['a=3*y+1'; 'x=a*z+y'])