How to output a for to a 10x27 table (for loop keeps overwriting the variable)

I am trying to iterate an equation using a range of values as a linspace(2, 3, 10) for one variable and set of 27 variable for the second variable.

The equation I am trying to iterate is assigned to a variable sigma_x_case1 (See Attached - Equation.png)

The For Loop that I currently have is as follows:

height_range_data = linspace(2, 3, 10);
diameter_range_data = [0.405, 0.54, 0.675, 0.84, 1.05, 1.315, 1.66, 1.9 ,2.375, 2.8753, 5, 4, 4.5, 5, 5.563, 6.625, 8.625, 10.75, 12.75, 14, 16, 18, 20, 24, 30, 36, 48];
d = diameter_range_data;
for h = height_range_data;
    sigma_x_case1_it1 = (subs(sigma_x_case1))
end

Unrecognized function or variable 'sigma_x_case1'.

*** EDIT ***

*** Should be a 10 row (h) by 27 (d) table ***

sigma_x_case1 is a equation that was solved using other variables... would I need to convert this equation to a function (d, h) to perform the loop?

Please see the attached code for reference (Question_Thompson_Marshall_AENG_502_Project_Calcs.mlx) - All imshow functions commented out so the code can run.

The output of the for loop gives me the correct values when d and h are subbed into the equation using the "subs" function; however, the output gives the "sigma_x_case1_it1" variable 10 times and when I try to call it, it outputs the last iteration which indicates that it is writing over it (See Attached - Output.png). How do I get the for loop to output a 10x27 table or array that I can eventually write to Excel? Do I need to have the for loop output sigma_x_case1_it1 as 27 seperate variable then combine somehow in a matrix or table? If so, how do I do that or is there any easier way to solve this.

Any help would be appreciated!

Marshall

[Image Analyst]

What is sigma_x_case1?

[Marshall Thompson]

sigma_x_case1 is an equation in terms of d and h that was solved with many other variables.

Answer 1

[Peter Perkins]

Marshall, the advice to try to vectorize is good advice, but if that's not possible, you might try something like at this:

height_range_data = linspace(2,3,10),

height_range_data = 1×10

2.0000 2.1111 2.2222 2.3333 2.4444 2.5556 2.6667 2.7778 2.8889 3.0000

diameter_range_data = [0.405,0.54,0.675,0.84,1.05,1.315,1.66,1.9,2.375,2.8753,5,4,4.5,5,5.563,6.625,8.625,10.75,12.75,14,16,18,20,24,30,36,48],

diameter_range_data = 1×27

0.4050 0.5400 0.6750 0.8400 1.0500 1.3150 1.6600 1.9000 2.3750 2.8753 5.0000 4.0000 4.5000 5.0000 5.5630 6.6250 8.6250 10.7500 12.7500 14.0000 16.0000 18.0000 20.0000 24.0000 30.0000 36.0000 48.0000

[h,d] = ndgrid(height_range_data,diameter_range_data);
h = h(:); d = d(:);
t = table(h,d)

t = 270×2 table
      h         d  
    ______    _____

         2    0.405
    2.1111    0.405
    2.2222    0.405
    2.3333    0.405
    2.4444    0.405
    2.5556    0.405
    2.6667    0.405
    2.7778    0.405
    2.8889    0.405
         3    0.405
         2     0.54
    2.1111     0.54
    2.2222     0.54
    2.3333     0.54
    2.4444     0.54
    2.5556     0.54

t2 = [t rowfun(@(h,d) h/d,t,OutputVariableName="Fun_hd")]

t2 = 270×3 table
      h         d      Fun_hd
    ______    _____    ______

         2    0.405    4.9383
    2.1111    0.405    5.2126
    2.2222    0.405     5.487
    2.3333    0.405    5.7613
    2.4444    0.405    6.0357
    2.5556    0.405      6.31
    2.6667    0.405    6.5844
    2.7778    0.405    6.8587
    2.8889    0.405    7.1331
         3    0.405    7.4074
         2     0.54    3.7037
    2.1111     0.54    3.9095
    2.2222     0.54    4.1152
    2.3333     0.54     4.321
    2.4444     0.54    4.5267
    2.5556     0.54    4.7325

You asked for a 10x27 array. You can easily turn this output into that, but depending on what you are doing after this, the above might (or might not) be a more convenient form.

[Marshall Thompson]

Thank you!

The output gives me a 270x3 table which is perfect for my analysis since that would be easiler to analyze the"Diameter Range" visually once I get the data to excel!

I am having trouble writing the table to excel...I am currently using these line of code to output the table and write to excel:

height_range_data = linspace(2, 3, 10);

diameter_range_data = [0.405, 0.54, 0.675, 0.84, 1.05, 1.315, 1.66, 1.9 ,2.375, 2.8753, 5, 4, 4.5, 5, 5.563, 6.625, 8.625, 10.75, 12.75, 14, 16, 18, 20, 24, 30, 36, 48];

[h,d] = ndgrid(height_range_data,diameter_range_data);

h = h(:);

d = d(:);

t = table(h,d);

sigma_x_iteration1 = [t rowfun(@(h,d) subs(sigma_x_case1),t,OutputVariableName="sigma_x_case1_it1")];

writetable(sigma_x_iteration1,excel_filename,"Sheet","Sigma_X (My) - IT 1");

The bolded line gives me an output table as shown in (Excel Table Output.png) where the sigma_x_case1_it1 values won't write to excel to Column C. I am confused since it is showing up in matlab as a 270x3 table so it should write the 3 coloumn of the table correctly but it seems like it is having issues with the values that are outputted from the subs(sigma_x_case1)? I've tried using "Range" in the writetable function as well as converting the 3rd column to an array using sigma_x_iteration{:,3} then back to table using array2table, then trying to writetable again but no luck.

Thanks!

[Marshall Thompson]

Disregard!

double(subs(sigma_x_case1)) converted the 1x1 syms in the sigma_x_iteration1 output variable and I was able to write that to excel.

Thank you so much for the help @Peter Perkins

Marshall

Answer 2

[Sulaymon Eshkabilov]

It can be computed using vectorization instead of loop - see this:

sigma_x_case1 = @(d, h)122.23*d.*(814.735*d+167.7312*h+335.4624) ./((d-1).^4-d.^4);
height_range_data = linspace(2, 3, 27);
h=height_range_data;
diameter_range_data = [0.405, 0.54, 0.675, 0.84, 1.05, 1.315, 1.66, 1.9 ,2.375, 2.8753, 5, 4, 4.5, 5, 5.563, 6.625, 8.625, 10.75, 12.75, 14, 16, 18, 20, 24, 30, 36, 48];
d = diameter_range_data;

[D, H] = meshgrid(d, h);
SS = sigma_x_case1(D,H);
surfc(D,H, SS)
xlabel('d')
ylabel('h')
zlabel('sigma_x_case1(d,h)')

[Marshall Thompson]

sigma_x_case1 is a equation based on many other variables so I can’t break it out and hard code the terms like you did since I will possibily need to change the input variables for futher analysis. Is there anyway I can apply the (d, h) to my sigma_x_case1 equation variable as a function and it will result in the same response?

Please see the attached file (Question_Thompson_Marshall_AENG_502_Project_Calcs.mlx) for all of the code.

Thanks