whats wrong with my code?

function v=velocity(x,y,z,t)
if and (length(x)==length(y), length(y)==length(z))
    if length(z)==length(t)
        v=sqrt(diff(x).^2+diff(y).^2+diff(z).^2)./diff(t);
        disp(velocity,sqrt)
    else
        disp('Vectors must have the same length for calculation');
    end
end

[Voss]

What is your intent with this line?

disp(velocity,sqrt)

That calls the function velocity() again, with no arguments (and the function sqrt() with no arguments), which causes an error.

Maybe you mean this instead?

disp(v)

Answer 1

[Image Analyst]

Well #1 is the lack of comments. All programmers should comment their code, and you should too.

Secondly, this

if and (length(x)==length(y), length(y)==length(z))

should be

    if (length(x)==length(y)) && (length(y)==length(z))

And the very first line inside the function should be

v = [];

so that you at least return something if the length test fails.

[daniel]

Unrecognized function or variable 'velocity'.

[Torsten]

disp(velocity,sqrt)

This statement does not make sense since "velocity" is the name of the function, but not of a variable that could be displayed.

Further, if such a variable existed, it had to be

disp(sqrt(velocity))

instead of

disp(velocity,sqrt)

[Image Analyst]

Like @Voss said, you need

disp(v)