Failed to resolve error: 'Dot indexing is not supported for variables of this type.'

I want to find various statistics for my data using CUPID. I am following instructions from Cupid.pdf documentation. Here is the code for obtaining standard deviation. I have attached the data. I have read some solutions to similar errors but have yet to relate them to my problem.

clc; close all; clear;
SpeedM = readmatrix("SpeedM.xlsx");
% addpath('C:\Users\user\AppData\Roaming\MathWorks\MATLAB Add-Ons\Toolboxes\Cupid');
x2 = linspace(0, max(SpeedM) + 1, 100); % Values for which to compute PDF
custpdf = @(x2,a,b,c) (x2>c).*(b/a).*(((x2-c)/a).^(b-1)).*exp(-((x2-c)/a).^b);
opt = statset('MaxIter',1e5,'MaxFunEvals',1e5,'FunValCheck','off');
phat = mle(SpeedM,'pdf',custpdf,'start',[0 0 0],'Options',opt,...
    'LowerBound',[0 0 -Inf],'UpperBound',[Inf Inf min(SpeedM)]);
pdf_values2 = custpdf(x2,phat(1),phat(2),phat(3))

pdf_values2 = 1×100

0 0.0214 0.0563 0.0861 0.1126 0.1361 0.1568 0.1745 0.1895 0.2017 0.2112 0.2181 0.2225 0.2245 0.2244 0.2223 0.2184 0.2129 0.2061 0.1982 0.1893 0.1797 0.1696 0.1591 0.1484 0.1377 0.1272 0.1168 0.1067 0.0970

Standarddeviatiation = pdf_values2.SD;

Dot indexing is not supported for variables of this type.

However, I am getting an error:

"Dot indexing is not supported for variables of this type."

I have followed links suggested here but failed to resolve the error. Please assist.

[Matt J]

Look at the output of your code above. pdf_values2 is a 1x100 numeric vector, not a struct.

Answer 1

[Sai Pavan]

Hi Chish,

I understand that you are trying to resolve the dot indexing error and calculate the standard deviation of the “pdf_values2” variable.

You are encountering the dot indexing error because you are trying to access the “SD” property of an array “pdf_values2”, which does not have such a property. The “pdf_values2” variable is a 1x100 array of probability density values, not a structure with a SD property.

Please refer to the below documentation to learn how to use dot indexing:

• https://www.mathworks.com/help/matlab/ref/struct.html
• https://www.mathworks.com/help/matlab/matlab_prog/indexing-into-function-call-results.html

Alternatively, you may try the “std” function to calculate the standard deviation. Please refer to the below code snippet to calculate the standard deviation of the “pdf_values2” array:

Standarddeviation = std(pdf_values2);

Please refer the below documentation to learn more about the “std” function:https://www.mathworks.com/help/matlab/ref/std.html

Hope it helps.

Regards,

Sai Pavan