Pass variables between functions

I have coded a script which should return the stiffness matrix (not done yet!) and I wonder how I can pass a matrix between various functions? (I don't want to type a giant matrix as an input parameter)

When I run it, it complains on the PB(Bmatrix,D) and KMatrix(D,Areaterm).

Thank you for your help!

clc 
clear all

%% Creating matrices holding some values for nodes and elements:

% Define Node Coordinates - change these values!
ConnectingNodes=[0.425 0;
    0.525 0;
    0.525 0.1;
    0.425 0.1;
    0.475 0.05];

% Connecting elements with 5 nodes:
ConnectingElements=[1 2 5;
    2 5 3;
    3 5 4;
    1 4 5];

%% Improvements:
% Creating if-else for the number of nodes (triangle)
% Ask the user for input i.e number of nodes etc..


%% Creating a nested for-loop for printing both the elements and nodes:
% Marking the nodes:
for a=1:length(ConnectingNodes)
    %Marking the elements:
    for b=1:length(ConnectingElements)
        r1=ConnectingNodes(ConnectingElements(b,1),1);
        z1=ConnectingNodes(ConnectingElements(b,1),2);
        r5=ConnectingNodes(ConnectingElements(b,2),1);
        z5=ConnectingNodes(ConnectingElements(b,2),2);
        r6=ConnectingNodes(ConnectingElements(b,3),1);
        z6=ConnectingNodes(ConnectingElements(b,3),2);
        plot([r1 r5 r6 r1],[z1 z5 z6 z1],'-black')
        [r_hat,z_hat]=centroid(polyshape([r1 r5 r6],[z1 z5 z6]));
        disp("Elements:" + length(ConnectingElements))

        %% Assembling the stiffness matrix:
    end

    plot(ConnectingNodes(a,1),ConnectingNodes(a,2))
    text(ConnectingNodes(a,1),ConnectingNodes(a,2),num2str(a))
    disp("Nodes:" + length(ConnectingNodes))
    hold on
end

%% Calling our functions:

%Parameters:
param(1,0,1.5,0.5,2,0)

%D-matrix:
D(210*10^9 , 0.3)

%Area:
AreaTerm(1,1.5,0,0,0.5,0)

%% Issues here!
%B-matrix:
PB(Bmatrix,D)

%K-matrix:
KMatrix(D,AreaTerm)

%% End of issues

% Declaring variables and size of cylinder:
p_rand = 3;
p = 60*10^6;
di = 850;
do = 1050;
L = 3*do;

%Nodal force:
NodalForce(p,p_rand,di,do,L)

%% Check here variable parsing - errors can be found here!

%% Parameter adjustment
function variable1 = param(r1,z1,r5,z5,r6,z6)

a1 = (r5*z6) - (z5*r6);
a5 = (r6*z1) - (z6*r1);
a6 = (r1*z5) - (z1*r5);

B1 = z5-z6;
B5 = z6-z1;
B6 = z1-z5;

Gamma1 = r6-r5;
Gamma5 = r1-r6;
Gamma6 = r5-r1;

% Doesn't do anything except printing a 3x3 matrix with our variables:
variable1 = [a1 a5 a6; B1 B5 B6; Gamma1 Gamma5 Gamma6];
disp("variables:")
disp(variable1)
end

%% Area:
function Area = AreaTerm(r1,r5,r6,z1,z5,z6)
%[rbar,zbar]=centroid(polyshape([ri rj rm],[zi zj zm]));
Area=area(polyshape([r1 r5 r6],[z1 z5 z6]));
disp("Area:" + Area)
end

%% D-matrix:
function DMatrix = D(E,v)
DMatrix = E/((1+v)*(1-(2*v)))*...
    [(1-v) v v 0;
 v (1-v) v 0;
 v v (1-v) 0;
 0 0 0 ((1-(2*v))/2)];

disp("D-matrix:")
disp(DMatrix)
end

%% B-Matrix:
function BMat = Bmatrix(Area,B1,B5,B6,Gamma1, Gamma5, Gamma6, z_hat,r_hat)
BMat = (1/(2*Area)).*[B1 0 B5 0 B6 0;
    0 Gamma1 0 Gamma5 0 Gamma6;
    ((a1/r_hat) + B1 + (Gamma1*z_hat/r_hat)) 0 ((a5/r_hat) + B5 + (Gamma5*z_hat/r_hat))...
    0 ((a6/r_hat) + B6 + (Gamma6*z_hat/r_hat)) 0;
    Gamma1 B1 Gamma5 B5 Gamma6 B6];

disp("B-Matrix:")
disp(BMat)
end

%% Product of the B and D matrix:
function ProdBD = PB(BMat,DMatrix)
BTrans = BMat';
ProdBD = BTrans*DMatrix;
disp("ProdBD:")
disp(ProdBD)
end

%% Nodal forces:
function NF = NodalForce(p,p_rand,di,do,L)
NF = pi*p_rand*L/p;
disp("NF:")
disp(NF)
end

Answer 1

[Torsten]

If you type

PB(Bmatrix,D)

then Bmatrix and D are inputs to the function PB. Thus they must somehow be defined before this call.

This in not the case in your code.