Having each iteration of nested loop plot on graph

I have a test script of a much larger script for one nested loop. The nested loop uses 3 different vectorized variables to find a Radius, then using the same variables and the new radius, determine a value. The value is summed for each possible combination of x and y for a given z. I wish to plot that summed value, the the loop will return to z and pick a new z, where the sum is reset. Once each z has been used, the plot should show the summed value at each z recorded on a single plot. When I use the loop, I am only getting the final value of sigma, and nothing plotted. Can someone figure out why my nested loop is failing?

clear;clc;

gamma = 95;

zwater = 0;

H = 10;

TYP = 1;

x = 8;

v = 0.49;

array = 2;

arraysize = 6;

Q = 250;

Q = (Q/array^2);

nax = array;

nay = array;

sum =0;

xmin = x - arraysize/2;

xmax = x + arraysize/2;

yleft = -(arraysize/2);

yright = (arraysize/2);

z = 0:0.1:H;

xa = linspace(xmin+(1/(2*array)*arraysize),xmax-(arraysize/(2*array)),nax);

ya = linspace(yleft+(1/(2*array)*arraysize),yright-(arraysize/(2*array)),nay);

for zii = z

sum =0;

for xii = xa

for yii = ya

R = sqrt(xii^2+yii^2+zii^2);

sigprimeh = ((Q/(R*pi))*((3*zii*xii^2)/R^3)*((R*(1-2*v))/(R+zii)));

sum = sum +sigprimeh;

figure()

end

end

plot(sigprimeh,z)

title('Stress Due to Surcharge Load')

xlabel('\sigma`h (ksf)');

ylabel('Depth "z"(ft)');

set(gca,'YDir','reverse')

hold on

end

Answer 1

[Tushar Behera]

Hi Mabin,

I assume you want to know why your code is not performing as you had expected.

Your code has a problem since you calculate the "sigprimeh" value inside the innermost loop, overwriting it after each iteration and only charting the final value. After computing the total for each "zii", you must relocate the assignment statement outside the innermost loop in order to plot the cumulative sum for each "zii" value. Also you should use an array to store the values of "sigmaprimeh" as that will preserve all the calculated values. For example:

clear;
clc;
gamma = 95;
zwater = 0;
H = 10;
TYP = 1;
x = 8;
v = 0.49;
array = 2;
arraysize = 6;

Q = 250;
Q = (Q/array^2);
nax = array;
nay = array;

xmin = x - arraysize/2;
xmax = x + arraysize/2;
yleft = -(arraysize/2);
yright = (arraysize/2);
z = 0:0.1:H;
sigma_h = zeros(1,length(z)); % Preallocate memory for sigma_h
xa = linspace(xmin+(1/(2*array)*arraysize),xmax-(arraysize/(2*array)),nax);
ya = linspace(yleft+(1/(2*array)*arraysize),yright-(arraysize/(2*array)),nay);

for ii = 1:length(z)
    sum =0;
    for xii = xa
        for yii = ya
            R = sqrt(xii^2+yii^2+z(ii)^2);
            sigprimeh = ((Q/(R*pi))*((3*z(ii)*xii^2)/R^3)*((R*(1-2*v))/(R+z(ii))));
            sum = sum +sigprimeh;
        end
    end
    sigma_h(ii) = sum;
end
plot(sigma_h,z)
title('Stress Due to Surcharge Load')
xlabel('\sigma`h (ksf)');
ylabel('Depth "z"(ft)');
set(gca,'YDir','reverse')

This will compute the accumulated sum for each "zii" value and store it in the "sigma_h" array, which can then be plotted against "z".

I hope this answers your question.

Regards,

Tushar

[Mabin]

That was it! Thanks!

Regards,

Mabin