Calcualting the tension in a wire

close all; clear all; clc
%Calculates tension in a cable
m=50; g=9.81; l=50;                             %Parameters are fixed for run
c=linspace(50,100,100);
d=linspace(0,l,100);                            %Vector for distance from wall
D=zeros(100,1);
Tmin=zeros(100,1);
for x=1:length(c);
tension=m*g*c(x)*l./(d.*sqrt(c(x)^2 - d.^2));   %Calculation
[a,b]=min(tension);
Tmin(x)=a;
D(x)=d(b);
end
plot(D,Tmin,'b')                                %Plot
[p,q]=min(Tmin);                                %To find minimum tension, and postn
output=['Minimum tension ', num2str(p), ' occurs at d=',  num2str(D(q)), ' Cable length ', num2str(c(q))];
disp(output)

Above is my code for calclulating the tension in a wire (different lengths). The resultant plot is similar to a staircase going downwards, but i am led to believe that it should be more parabolic...could anyone shed any light on the situation, thank you.

EDIT:

m=mass g=gravity l=length of beam c=length of cable Tmin=minimum tension a,b = minimum tension, a, at location, b.

[Mischa Kim]

Could you post the equations you are working with? That would make it easier for those of us that are not that deep into structures.

[matt]

I have edited the original to include what each property is. I presume this is what you meant by equations as i dont have anything else to work with.

[Mischa Kim]

I was talking about the "original" equations from a paper or textbook, a scan or photo would do. Not sure but I think the staircase behavior could be due to the min function.

[Star Strider]

You’re plotting the minimum over the interval. It’s going to be discontinuous by definition.

It’s a Catenary.

[matt]

I dont have anything to work with, all i have been told is that i am to find the cable length, its position, and the distance from the wall.

[matt]

I am asked to plot graphs of: cable length against minimum tension and position d.

Answer 1

[Roger Stafford]

The "staircase" effect you are getting is due to the fact that your minimum always occurs at the far end where d = 1, since the tension is always monotone decreasing for the d values you are using. Consequently you get a vertical line for the plot. You are very far from reaching the true minimum at d = c/sqrt(2). If you did have d ranging that far, you would get a hyperbolic, not parabolic, curve of minimum tension versus d.