How to plot exact user defined function?

I have defined a function like this

function z=agni(x)
if x > 0
    z=x;
else
    z = x.^2;
end

But in the time of plotting plot(x,agni(x)) with x =[-2:.01:2] generate only the curve of x^2. WHY?

Answer 1

[Walter Roberson]

if x > 0

means

if all(x > 0)

so if you pass in a vector of x then if any x in the vector is <= 0 then the "if" will not be true.

You should research logical indexing.

[Agniswar]

Then what can I do to plot a composite function?

Answer 2

[Serge Boisse]

Hello, You should understand that your function accepts a vector of values, not a scalar. then it must return a vector of the same length (that will be plotted) So you may rewrite your function as follows :

function z=agni(x)
 z = x; % this is a vector !
 ind = (x<0); % logical array : 1 if corresponding element of x is <0
 z(ind) = z(ind).^2;
end

Hope this helps. If you prefer to code functions "the classical way", have a look at symbolic functions.