Creating a function with endless errors

function [A2, V_inj, N, A2_tot] = OrfG(mdot, x)
%function
global d
global rho
global k
global deltap
A2 = pi*(d^2/4); 
V_inj = sqrt((2*deltap)/(k*rho));
n_temp = mdot /(rho*V_inj*A2); 
if x == 0
    y = 0;
else 
    y = 1;
end  
N = ceil(n_temp) + y;
A2_tot = N*A2;
end

Then I run

[q, w, r, t] = OrfG(1.53, 0)

I see

>> OrfG(1.53, 0)
Error using  / 
Matrix dimensions must agree.

Error in OrfG (line 18)
n_temp = mdot /(rho*V_inj*A2); 

if I change the code to

n_temp = mdot ./(rho*V_inj)*A2);

and run the same code it shows me a bunch of empty matrices.

[KSSV]

Why you want to use global? Try to avoid it.

Answer 1

[KSSV]

YOu have to define the global variables...

global d
global rho
global k
global deltap

As you have not defined them,, they will be taken as empty i.e [].

Answer 2

[madhan ravi]

Don't use global variables it's a bad practise , learn to parameterize functions.

See Parameterize function to better understand

d = somevalue;
rho= somevalue;
k= somevalue;
deltap= somevalue;
[A2, V_inj, N, A2_tot] = OrfG(mdot, x,d,rho,k,deltap) % function call just paramterize 


function [A2, V_inj, N, A2_tot] = OrfG(mdot, x,d,rho,k,deltap)
%function
A2 = pi*(d^2/4); 
V_inj = sqrt((2*deltap)/(k*rho));
n_temp = mdot /(rho*V_inj*A2); 
if x == 0
    y = 0;
else 
    y = 1;
end  
N = ceil(n_temp) + y;
A2_tot = N*A2;
end