Info

此问题已关闭。 请重新打开它进行编辑或回答。

What is wrong with my code?

1 次查看（过去 30 天）
Ibrahim Butt
Ibrahim Butt 2020-10-25
关闭： MATLAB Answer Bot 2021-8-20
% It finds the velocity using RK 4 method
clc; % Clears the screen
clear all;
h = input('Insert the value of the step size: '); % step size
t = 0:h:20; % Calculates till v(20)
v = zeros(1,length(t));
v(1) = input('Insert the value of the initial velocity: '); % initial condition
F_xy = @(v,t) 9.81 - ((0.28/85) * (v^2));
for i=1:(length(t)-1) % calculation loop
k_1 = F_xy(t(i),v(i));
k_2 = F_xy(t(i)+0.5*h,v(i)+0.5*h*k_1);
k_3 = F_xy((t(i)+0.5*h),(v(i)+0.5*h*k_2));
k_4 = F_xy((t(i)+h),(v(i)+k_3*h));
v(i+1) = v(i) + (1/6)*(k_1+2*k_2+2*k_3+k_4)*h % main equation
end

请先登录，再回答此问题。

回答（2 个）

Cris LaPierre
Cris LaPierre 2020-10-25
Ran in:
Nothing. It's doing exactly what you've told it to do.
You specified a stepsize of 0 (variable h).
This causes t to be an empty vetor.
t=0:0:20
t = 1×0 empty double row vector
This causes your for loop to never run, since 1:(length(t)-1) simplifies to 1:-1.
Alan Stevens
Alan Stevens 2020-10-25
Your code works if you put in sensible numbers for step size and velocity.
Zero is not sensible!

标签

产品


版本

R2019a

Community Treasure Hunt

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

Start Hunting!

Translated by