Element Wise Matrix multiplication issue (.*)
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Yuvraaj Pasumarthy
am 17 Sep. 2023
Beantwortet: Sam Chak
am 25 Sep. 2023
EDIT: Extremely sorry about not providing the values, still very new to MATLAB and its community
B=0.5
u=2
zeta= 0.1 to 1 with an increment of 0.01
r= 0.01 to 100 with no specific increments
M=sqrt((square(1-B^2.*(r.^2))*(1+4.*((zeta*r).^2)))/square(1-((((1+u)*B^2)+1).*(r.^2))+(B^2.*(r.^4)))+4*((zeta*r).^2)*square(1-(1+u)*(B^2.*(r.^2))));
ERROR:
Incorrect dimensions for matrix multiplication. Check that the number of columns in the first matrix matches the number of rows in the second matrix. To operate on each
element of the matrix individually, use TIMES (.*) for elementwise multiplication.
2 Kommentare
Dyuman Joshi
am 17 Sep. 2023
Please provide the variables used to define M.
I suspect the error occurs because you are trying to multiply two same sized vectors (zeta and r)
Dyuman Joshi
am 17 Sep. 2023
Bearbeitet: Dyuman Joshi
am 17 Sep. 2023
@Yuvraaj Pasumarthy, zeta and r are not compatible for matrix multiplication or element-wise multiplication.
zeta= 0.1:0.01:1;
size(zeta)
r= 0.01:100;
size(r)
Akzeptierte Antwort
Sam Chak
am 17 Sep. 2023
Bearbeitet: Sam Chak
am 18 Sep. 2023
Update: With the values of zeta, beta, and mu provided, you can plot something. You can try experimenting yourself.
% Assigning parameters
zeta = [0.05, 0.1, 0.3, 0.5, 1];
beta = 0.5;
mu = 2;
r = logspace(-2, 2, 4001);
% Setup a repetitive looping task using the for-loop method
% the task is to generate logy-logx plot 5 times, as numel(zeta) = 5
for i = 1:numel(zeta)
M = sqrt((1 + 4*(zeta(i)^2)*(r.^2)).*(1 - (beta^2)*(r.^2)).^2)./sqrt((1 - ((1 + mu)*beta^2 + 1)*r.^2 + (beta^2)*(r.^4)).^2 + 4*(zeta(i)^2)*(r.^2).*(1 - (1 + mu)*(beta^2)*(r.^2)).^2);
txt = ['\zeta = ', num2str(zeta(i))]; % for legend purposes
loglog(r, M, 'DisplayName', txt)
hold on % retain the current plot window so that next graph can be plotted
end
% Labelling stuffs
grid on % toggle grid on
hold off
ylim([1e-4 1e2]) % set y-axis limit for display purposes (same as your image)
xlabel('Frequency ratio, r')
ylabel('Vibration transmissibility, F_{2}/F_{0}')
legend show
9 Kommentare
Sam Chak
am 25 Sep. 2023
You are welcome! You can change the values for beta β and mu μ on Lines 3 and 4 as indicated below:
% Assigning parameters % <-- Line 1
zeta = [0.05, 0.1, 0.3, 0.5, 1]; % <-- Line 2
beta = 0.5; % <-- Line 3
mu = 2; % <-- Line 4
r = logspace(-2, 2, 4001); % <-- Line 5
Weitere Antworten (1)
Sam Chak
am 25 Sep. 2023
If you want to examine the effects of varying the beta values while keeping zeta and mu fixed, the structure of the code remains the same; however, you'll loop around beta instead of zeta.
% Assigning parameters
zeta = 0.5;
beta = [0.1, 0.3, 0.5, 0.7, 0.9];
mu = 2;
r = logspace(-2, 2, 4001);
% Setup a repetitive looping task using the for-loop method
% the task is to generate logy-logx plot 5 times, as numel(zeta) = 5
for i = 1:numel(beta)
M = sqrt((1 + 4*(zeta^2)*(r.^2)).*(1 - (beta(i)^2)*(r.^2)).^2)./sqrt((1 - ((1 + mu)*beta(i)^2 + 1)*r.^2 + (beta(i)^2)*(r.^4)).^2 + 4*(zeta^2)*(r.^2).*(1 - (1 + mu)*(beta(i)^2)*(r.^2)).^2);
txt = ['\beta = ', num2str(beta(i))]; % for legend purposes
loglog(r, M, 'DisplayName', txt)
hold on % retain the current plot window so that next graph can be plotted
end
% Labelling stuffs
grid on % toggle grid on
hold off
ylim([1e-4 1e2]) % set y-axis limit for display purposes (same as your image)
xlabel('Frequency ratio, r')
ylabel('Vibration transmissibility, F_{2}/F_{0}')
title('Variation of \beta while keeping \zeta and \mu fixed')
legend show
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