hi

i follow Julia-'s help on http://docs.julialang.org/en/stable/manual/functions/ and i try to inderstand how functions work in Julia

i type this in a file that i run with an `include`

in the RPPL :

```
function f(x,y)
x + y
end
f(2,3)
```

it seems to work but Julia says :

WARNING: Method definition f(Any, Any) in module Main at /Users/vincentdouce/Desktop/Julia/vademecum_Julia.jl:16 overwritten at /Users/vincentdouce/Desktop/Julia/vademecum_Julia.jl:16.

i must admit i do not undestand at all what it means, and i pain to find any explanation on `http://docs.julialang.org`

about this point.

morehowever, i type this :

```
function f(x)
x*2
end
f(2,3)
```

and the result is 5.

i am ok that my script is wrong according to the number of variables of f, but why 5 ?

de plus je ne parviens pas du tout à comprendre comment tracer une famille de fonctions. Par exemple si je veux tracer les courbes f(x)=a.cos(x) pour a variant

j’ai essayé :

```
1 function f(x,y)
2 return(x*cos(y))
3 end
4
5 tvec = linspace(-π,π , 100)
6 for i=-5:5
7 plot!(tvec, f(i,tvec))
8 end
```

but the result is :

`WARNING: Method definition f(Any, Any) in module Main at [line 2] overwritten at [line 2]`

???

thanks for your help