Creating a function with endless errors

Question

Vignesh Sella 2018-12-4

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/433684-creating-a-function-with-endless-errors

编辑： madhan ravi 2018-12-4

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.

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KSSV 2018-12-4

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

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Answer 1

KSSV 2018-12-4

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https://ww2.mathworks.cn/matlabcentral/answers/433684-creating-a-function-with-endless-errors#answer_350398

在 MATLAB Online 中打开

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 [].

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Answer 2

madhan ravi 2018-12-4

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/433684-creating-a-function-with-endless-errors#answer_350400

编辑：madhan ravi 2018-12-4

在 MATLAB Online 中打开

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