feval multiple evaluation

## Syntax

    [z]=feval(x,y,f)
                [z]=feval(x,f)

## Arguments

x,y

  two vectors

f

  a function or a character string (for Fortran or C call)

## Description

Multiple evaluation of a function for one or two arguments of vector type :

z=feval(x,f)

  returns the vector `z` defined by `z(i)=f(x(i))`

z=feval(x,y,f)

  returns the matrix `z` such as `z(i,j)=f(x(i),y(j))`

`f` is an external (function or routine) accepting on one or two arguments which are supposed to be real. The result returned by `f` can be real or complex. In case of a Fortran call, the function `f` must be defined in the subroutine `fevaltable.c` (in directory `SCI/modules/differential_equations/src/c`).

## Examples

    deff('[z]=f(x,y)','z=x^2+y^2');
    feval(1:10,1:5,f)
    deff('[z]=f(x,y)','z=x+%i*y');
    feval(1:10,1:5,f)
    feval(1:10,1:5,'parab')   //See ffeval.f file
    feval(1:10,'parab')
    // For dynamic link (see example ftest in ffeval.f)
    // you can use the link command (the parameters depend on the machine):
    // unix('make ftest.o');link('ftest.o','ftest'); feval(1:10,1:5,'ftest')

## See also

- evstr
- horner
- execstr
- external
- link