showing error " Array indices must be positive or logical values"

Question

Prasannakumar reddy 2024-4-4，14:11

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2102926-showing-error-array-indices-must-be-positive-or-logical-values

移动：VBBV 2024-4-5，5:16

clc
clear all
N=2;
c=linspace(0.035,0.010,21)
r=linspace(0.0001,1,21)
thetaroot=15;
thetatip=4;
a=5.7
R=0.35;
theta=(thetaroot+(r.*(thetatip-thetaroot)))./57.3
sigma=(N.*c(i))./(pi.*R)
lambda=sigma.*a((sqrt(1+32.*theta.*r)./(sigma(i).*a))-1)

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

VBBV 2024-4-4，15:10

移动：VBBV 2024-4-5，5:16

在 MATLAB Online 中打开

i & j are complex quantities in Matlab, if you use it as index without assigning any value to them would give such error, since Matlab uses 1 based positive integer indexing

clc
clear all
N=2;
c=linspace(0.035,0.010,21);
r=linspace(0.0001,1,21);
thetaroot=15;
thetatip=4;
a=5.7;
R=0.35;
theta=(thetaroot+(r.*(thetatip-thetaroot)))./57.3;
sigma=(N.*c)./(pi.*R)  % i & j are complex quantities in Matlab
sigma = 1x21
    0.0637    0.0614    0.0591    0.0568    0.0546    0.0523    0.0500    0.0477    0.0455    0.0432    0.0409    0.0387    0.0364    0.0341    0.0318    0.0296    0.0273    0.0250    0.0227    0.0205    0.0182
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
lambda=sigma.*a((sqrt(1+32.*theta.*r)./(sigma.*a))-1) % same in this line 
Array indices must be positive integers or logical values.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Torsten 2024-4-4，14:13

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2102926-showing-error-array-indices-must-be-positive-or-logical-values#answer_1436546

编辑：Torsten 2024-4-4，14:15

lambda=sigma.*a.*((sqrt(1+32.*theta.*r)./(sigma(i).*a))-1)

instead of

lambda=sigma.*a((sqrt(1+32.*theta.*r)./(sigma(i).*a))-1)

And since "i" is undefined, c(i) and thus sigma(i) are empty.

2 个评论
显示无隐藏无

Prasannakumar reddy 2024-4-4，14:22

thanks it's working.

Image Analyst 2024-4-4，14:27

If this Answer solves your original question, then could you please click the "Accept this answer" link to award the answerer with "reputation points" for their efforts in helping you? They'd appreciate it. Thanks in advance. 🙂 Note: you can only accept one answer (so pick the best one) but you can click the "Vote" icon for as many Answers as you want. Voting for an answer will also award reputation points.

请先登录，再进行评论。