I know there are commands to use when finding the max values within an array, how would I do it through data from a graph?

%%% Data Give Within Question
a = 7;
b = 3;
x = [0,b];
N = 100;
y = 0;

%%% d2f(x) = -(20+(a*f(x)))*x*(x-b);

% Choosing appropriate value for discretization step h
h = 0.01;
for n=0:N
    X(n+1) = h*n;
end

% Boundary Conditions
ua = 0;
ub = 0;

% Zero the A, u and B arrays
A = zeros(N+1,N+1);
B = zeros(N+1,1);
A(1,1)=1;
A(N+1,N+1)=1;
B(1)= ua;
B(N+1)= ub;

for n=2:N
    A(n,n)=-2/h^2-a*X(n)^2+a*X(n)*b; % main diagonal
    A(n,n+1)=1/h^2+X(n)/(2*h); % top diagonal
    A(n,n-1)=1/h^2-X(n)/(2*h); % bottom diagonal
    B(n)=20*X(n)*b - 20*X(n)^2;
end

U = linsolve(A,B);

plot(X,U,'--o')

Answer 1

[Torsten]

I know there are commands to use when finding the max values within an array, how would I do it through data from a graph?

By using the array you plot the graph with.

Answer 2

[Pratham Shah]

Why don't you use Min/Max function on the variable you are plotting. That will give you min/max value along with the corresponding index.