Array indices must be positive integers or logical values.

2022 3 6
2 个回答
更新时间：2022 3 6
3 次查看（30 天）

0 个投票

Error in TASKA (line 22)
A(t)=(A0-B0/YB)./(1-(B0/(YB*A0))*exp(-((YB*A0/B0)-1)*K*B0.*t));

5 个评论
显示 3更早的评论 隐藏 3更早的评论

David Hill
David Hill 2022-3-6
What is the value of t? The only thing you are indexing into is A. The error appears to tell you that t is not a positive integer or logical value.
David Hill
David Hill 2022-3-6
You cannot index with 0 (indexing for matlab starts at 1)
my initial value is 0 and final value is 12 hours i need to find the value inbetwwen this time
David Hill
David Hill 2022-3-6
Cannot help further unless you provide more information (all variables with values and context)

请先登录，再进行评论。

请先登录，再回答此问题。

回答（2 个）

Image Analyst
Image Analyst 2022-3-6

0 个投票

A thorough discussion is in the FAQ:
https://matlab.fandom.com/wiki/FAQ#.22Subscript_indices_must_either_be_real_positive_integers_or_logicals..22
In the meantime, try getting rid of (t) on the left hand side.
A = (A0-B0/YB) ./ (1-(B0/(YB*A0)) .* exp(-((YB*A0/B0)-1)*K*B0 .* t));

0 个投票

clc
clear all
YB=1;
YP=0.15;
A0=1;
B0=3;
P0=0;
K= 5E-5;
ti=0;
tf=12;
F=@(t,y)[-K*y(1)*y(2);-YB*K*y(1)*y(2);YP*K*y(1)*y(2)];
% create function of ODE
% f = [da/dt;db/dt,dp/dt]
[t,y]= ode89(F,[ti tf],[A0;B0;P0]);
%ODE89
A(t)=(A0-B0/YB)/(1-(B0/(YB*A0))*exp(-((YB*A0/B0)-1)*K*B0*tf));
% Analytical solution
plot(tf,y(:,1),'-0',tf,A_t','-*')
title('Solution of ODE with ODE89 and comparison with Analytical value');
xlabel('Time t');
ylabel('solution A(ODE89)& A(t) Analytical Value');
xlabel('Time t');
ylabel('solution A (ODE89) & A(t) Analytical value');
xlabel('Time t');
ylabel('Solution A(ODE89) & A(t) Analytical ');
legend('A(ODE89)','A(t) Analytical')
disp('time A(ODE89) A(t) Analytical ')
disp([tf y(:,1) A_t])

3 个评论
显示 1更早的评论 隐藏 1更早的评论

Image Analyst
Image Analyst 2022-3-6
编辑：Image Analyst 2022-3-6
You posted this as the "Answer".
So, did this "Answer" of your fix it? Otherwise take another look at my answer.
I tried using removing t in A but it shows
Error using plot
Invalid color or line style.
Error in TASKA (line 26)
plot(tf,y(:,1),'-0',tf,A,'-*')
Walter Roberson
Walter Roberson 2022-3-6
Ran in:
Ran in:
plot(rand(1,5), '-o')
plot(rand(1,5), '-O')
plot(rand(1,5), '-0')
Error using plot
Invalid color or line style.
which is to say that your '-0' is dash-zero and that is not a recognized line style or color. Using dash-oh or dash-capital-oh is fine.

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Ordinary Differential Equations 的更多信息

产品

版本

R2021b

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by