How to fix matrix dimensions

Question

Jonathon Klepatzki 2024-4-10，18:56

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2105356-how-to-fix-matrix-dimensions

移动：Rik 2024-4-11，4:16

Given the specific values of y, sigmay, and sigmaz (see code), I must calculate them and plot each line on a graph

close all;
clear all;
clc
Q = 1;
y = [10, 20, 30, 40, 50, 65, 80, 100, 200, 300, 400, 500, 650, 800, 1000];
sigmay = [27, 62, 115, 165, 210];
sigmaz = [14, 38, 105, 250 450];
u = 2;
for j = 1:y
    for k = 1:sigmay
        for l = 1:sigmaz
            C = (Q./pi.*sigmay.*sigmaz.*u).*exp(-0.5.*(y./sigmay).^2); %% this is where the error is at%%
        end
    end
end
Warning: Colon operands must be real scalars. This warning will become an error in a future release.
Warning: Colon operands must be real scalars. This warning will become an error in a future release.
Warning: Colon operands must be real scalars. This warning will become an error in a future release.
Arrays have incompatible sizes for this operation.
plot(y,C)
title('Excercise 1')
xlabel('distance (m)')
ylabel('concentrations')
grid on

As you can see, I tried using the ./ or .* but, it didn't work.

4 个评论
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Stephen23 2024-4-10，20:03

"Any suggestions?"

Do you have a reference for the formula?

Jonathon Klepatzki 2024-4-10，20:10

Just this, C = (Q/pi*sigmaz*sigmay*u)*exp(-1/2(y/sigmay)^2)

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Answer 1

the cyclist 2024-4-10，21:22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2105356-how-to-fix-matrix-dimensions#answer_1439591

移动：Rik 2024-4-11，4:16

在 MATLAB Online 中打开

In this expression

Q/pi*sigmaz*sigmay*u

only pi is going to be in the denominator.

Since your expression bears some resemblance to the PDF of a normal distribution, I expect that at least sigmaz and sigmay are also supposed to be in the denominator. Probably u as well.

I expect that you actually need

Q/(pi*sigmaz*sigmay*u)

which would give

Q = 1;
y = [10, 20, 30, 40, 50, 65, 80, 100, 200, 300, 400, 500, 650, 800, 1000];
sigmay = [27, 62, 115, 165, 210];
sigmaz = [14, 38, 105, 250 450];
u = 2;
C = (Q./(pi.*sigmay.*sigmaz.*u)).*exp(-0.5.*(y(:)./sigmay).^2)
C = 15x5
1.0e-03 *

    0.3931    0.0667    0.0131    0.0039    0.0017
    0.3200    0.0641    0.0130    0.0038    0.0017
    0.2271    0.0601    0.0127    0.0038    0.0017
    0.1405    0.0549    0.0124    0.0037    0.0017
    0.0758    0.0488    0.0120    0.0037    0.0016
    0.0232    0.0390    0.0112    0.0036    0.0016
    0.0052    0.0294    0.0103    0.0034    0.0016
    0.0004    0.0184    0.0090    0.0032    0.0015
    0.0000    0.0004    0.0029    0.0019    0.0011
    0.0000    0.0000    0.0004    0.0007    0.0006
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