How to enter this program in matlab?

Question

user1996 2014-10-24

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/159967-how-to-enter-this-program-in-matlab

回答： user1996 2014-10-26

Projectile motion equations describe: X= v0* cos(fi)*t Y= v0*sin(fi)*t-0,5*g*t Where g = 9.81 m / s2. Create a program that graphically shows the trajectory of the projectile entered the value of the angle and the initial speed of 5 m / s. (The calculation by adding the condition that the calculation ends if y <= 0 If !. plot function call in each step of the loop, it is desirable to define the fixed before the loop spans the axes)

2 个评论
显示无隐藏无

James Tursa 2014-10-24

What have you done so far? Typically, you would make an attempt and post your code so we can comment on it and suggest corrections and improvements. See this link:

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

user1996 2014-10-25

I'm sorry. this is what i have entered: Clc clear all g=9.81; v0=5; (Fi)= input('Enter the value of the angle:'); t0=v0*sin(fi)/g; while y>0; if y<=0 break; X=v0*t*cos(fi); Y=v0*t*sin(fi)-g*t^2/2 End Plot(X,Y); Title('projetile motion'); xlabel('range X(m)); ylabel('height Y(m)); End I don't know which loop should I use. Because the first time I used For j=0:100; i=j+1; t(i)=j*t0/100; Then i realised that was wrong beacasue I haven't used condition y<=0 Thank you for your time to answer me.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Rick Rosson 2014-10-25

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/159967-how-to-enter-this-program-in-matlab#answer_156521

在 MATLAB Online 中打开

Here's a start:

   g = 9.81;
   v0 = 5;
   phi = ...
   x = 0;   
   y = 0;
   while y > 0
       ...
       ...
   end

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

user1996 2014-10-25

Thank you a lot.

请先登录，再进行评论。

Answer 2

Rick Rosson 2014-10-25

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/159967-how-to-enter-this-program-in-matlab#answer_156574

编辑：Rick Rosson 2014-10-25

在 MATLAB Online 中打开

Your original MATLAB code

Here is the code as you posted it with a bit of improved formatting to make it more readable:

   Clc 
   clear all 
   g=9.81; 
   v0=5; 
   (Fi)= input('Enter the value of the angle:'); 
   t0=v0*sin(fi)/g; 
   while y>0; 
       if y<=0 break; 
       X=v0*t*cos(fi);
       Y=v0*t*sin(fi)-g*t^2/2 
   End 
   Plot(X,Y); 
   Title('projetile motion'); 
   xlabel('range X(m)); 
   ylabel('height Y(m));
   End

A few issues with your code

1. MATLAB is case-sensitive. Most keywords, commands, and built-in functions must be lowercase. So, in your code, please change:

Clc to clc
End to end
Plot to plot
Title to title

2. Please delete the semicolon at the end of the while statement. It is not necessary and may cause an error.

3. The input arguments that you are passing to xlabel and ylabel are supposed to be single-quoted strings, but they are missing the closing quotation mark. All strings must start and end with a single quote character.

4. Please delete the very last line of code. It is a simple end statement, but it appears to be unnecessary, and it will cause an error.

5. You have used the variable t inside the while loop but you have never defined or initialized t. Please define and initialize t before you use it. You will also want to increment the value of t during each iteration of the loop.

6. Likewise, please define and initialize y before the while loop, which uses y to evaluate the logical condition that controls when the loop terminates.

If you make all of these changes to your code, I believe the code will run in MATLAB. Although you have a very good start, you will need to add a few things to get the correct answer. You are almost there. Keep going.

2 个评论
显示无隐藏无

Guillaume 2014-10-25

在 MATLAB Online 中打开

In addition, the line

if y<=0 break;

is unnecessary since inside the body of the while loop y is guaranteed to be >0 (otherwise the loop wouldn't be entered in the first place).

Rick Rosson 2014-10-25

Yes, good point.

请先登录，再进行评论。

Answer 3

user1996 2014-10-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/159967-how-to-enter-this-program-in-matlab#answer_156647

Thank you for your time, I will try to find what I am missig out. Yes I know that I don't need the conditon y<=0 when I have while y>0. I just put it because that stands in the task. Again thnaks.