Finding Corresponding X Value for Y value

Looking to find the corresponding X value for the maximum force P in my force vs. displacement graph.

P=zeros(1,750);

theta=zeros(1,750);

L=zeros(1,750);

F=zeros(1,750);

W=10;

g=9806;

for x = 1:750

theta(x)=atand(400/x);

L(x)=sqrt((x^2)+(400^2));

F(x)=W*g*cosd(theta(x))*500;

P(x)=F(x)/L(x);

end

plot(1:750,P)

xlabel('x in mm')

ylabel('P in kg/mm/s^2')

Pmax= max(P);

fprintf('The maximum P value in kg/mm/s^2 is: %0.2f \n',Pmax);

Answer 1

[Les Beckham]

If you ask for two outputs from the max() function you can find the index of your peak:

P=zeros(1,750);
theta=zeros(1,750);
L=zeros(1,750);
F=zeros(1,750);
W=10; 
g=9806; 
for x = 1:750
    theta(x)=atand(400/x);
    L(x)=sqrt((x^2)+(400^2));
    F(x)=W*g*cosd(theta(x))*500;
    P(x)=F(x)/L(x);
end
plot(1:750,P)
xlabel('x in mm')
ylabel('P in kg/mm/s^2')

[Pmax, index] = max(P);
fprintf('The maximum P value in kg/mm/s^2 is: %0.2f at x = %d mm\n', Pmax, index);

The maximum P value in kg/mm/s^2 is: 61287.50 at x = 400 mm