How I can return output from function 'A' for using them as input for another function 'B'?

Hi! Kindly ask to help with return variable from function

I want to return data of 'I' from function 'A' and use it as an input for another function 'B'. Appreciate any help or useful documnetation. I have tried handle function, but failed. I suppose handle is for defined functions in MAtlab such as sin, cos, etc

function(I, j0) = calculation(x,y,z,j) %function 'A'

I = x + y + z;

R = I*j;

end

Then I am trying to return 'I' from function 'calculation' and use it as input for 'row' function

function( A,B,C ) = row(I, j0) %function 'B'

%I is point with coordinates

A= ...;

B = ....;

C= ...;

end

[Stephen23]

"I have tried handle function, but failed."

I don't see how a function handle would help return output arguments from a called function.

"I suppose handle is for defined functions in MAtlab such as sin, cos, etc"

You can define a function handle for any function. This is shown in the documentation:

https://www.mathworks.com/help/matlab/matlab_prog/creating-a-function-handle.html

[Aknur]

Hi @Stephen23 thank you for your time

According to this documentation I can write variable which will be equal to output of function, right?

f = @computeSquare;

a = 4;

b = f(a)

[Stephen23]

"According to this documentation I can write variable which will be equal to output of function, right?"

I don't know what that means. According to the documentation you can define a function handle to an existing function, you can then call that function handle. It is unclear what you want to explain by copying part of the example from that page.

[Aknur]

@Stephen23 thank you, now I understand. Can I ask function hadle should be written in that existing function inside. Or it should be written such as an another function

Or I write function handle in the beginning of another fucntion and then call haninsdle.

Here is my code and I want to return 'I - intersection point' instead of X0, Y0, Z0 to calculate next ray

X(i) = I(1);

Y(i) = I(2);

Z(i) = I(3);

And it becomes very difficult for me to understand how to return I and where should write handle. Could you please look at my code and give an advice how 'I should change it

Thank you in advance,

X0=1.5

Y0= 1.5

Z0 =3.0

Theta0 =30

Phi0 =90

K = 2 number of rays

this code works only for one ray

function [X, Y, Z, Theta, Phi, I, Rr] = reflection2(X0, Y0, Z0, Theta0, Phi0, K)

X = [X0 zeros(1,K)];

Y = [Y0 zeros(1,K)];

Z = [Z0 zeros(1,K)];

Theta = [Theta0 zeros(1,K)];

Phi = [Phi0 zeros(1,K)];

end

[Stephen23]

Can I ask function hadle should be written in that existing function inside. Or it should be written such as an another function Or I write function handle in the beginning of another fucntion and then call haninsdle."

A function handle can be defined anywhere where that function is within scope.

"Here is my code and I want to return 'I - intersection point' instead of X0, Y0, Z0 to calculate next ray.. And it becomes very difficult for me to understand how to return I and where should write handle."

It is very easy to return I, because it is already defined as the sixth output argument of that function:

function [X, Y, Z, Theta, Phi, I, Rr] = reflection2(X0, Y0, Z0, Theta0, Phi0, K)
%                              ^ the 6th output is what you want

So you can obtain that output by simply calling the function (or its handle) with whatever outputs you want:

[~,~,~,~,~,I_out] = reflection2
%          ^^^^^ call the function with any outputs that you require

How to call functions with output arguments is explained in the introductory tutorials:

https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

It is still unclear how function handles are relevant to this task.

[Aknur]

Hello, @Stephen23 thank you. Now I understand. Your help was very valuable, and thank you for sharing useful documentation

Answer 1

[Stephen23]

How to call function with output arguments is explained in the introductory tutorials:

https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

How to define function output arguments is explained in the FUNCTION() documentation:

https://www.mathworks.com/help/matlab/ref/function.html

I had to change your parentheses for the correct square brackets and define one of the output arguments:

x_in = 1;
y_in = 2;
z_in = 3;
j_in = 4;
[I_out,j0_out] = calculation(x_in,y_in,z_in,j_in)

I_out = 6

j0_out = 0

[A_out,B_out,C_out] = row(I_out, j0_out)

A_out = 1

B_out = 2

C_out = 3

function [I,j0] = calculation(x,y,z,j)
I = x + y + z;
j0 = 0; % you need to define all output arguments.
% R = I*j; % completely unused
end
function [A,B,C] = row(I, j0) % these input are unused.
A = 1;
B = 2;
C = 3;
end

[Aknur]

Dear @Stephen23 kindly ask why this

'(I, j0) % these input are unused.'

Because I want to use I,j0 to calculate 'row' function.

Real formulas and data are different, they are longer, so I decide to write example. Sorry if I confused you.