Can somebody help me get this to work in a loop???

1 次查看（过去 30 天）
mark
mark 2013-11-28
回答： Walter Roberson 2013-11-29
I'm trying to solve momentum transfer for a range of data. The basis of the script is:
  • Output a value as the phase angle (Th_D) shifts from 0 to 360
  • This, along with some other data, is solved using the simultaneous operator solve( ) ( 2 equations so 2 outputs )
  • The 2 outputs from solve are placed into a separate matrix that I can manipulate later
Or, to place it into steps:
  1. Calculate the value of Veff at phase angle Th_D (store the output in a matrix)
  2. From a specified value of Veff ( 2nd value in every column) substitute it into solve( )
  3. solve() will output this value and store it in B1 and B2
  4. k is increased and the loop restarts
  5. New value of phase angle is used to compute Veff.. etc
I can get the script to work with just one value but I've been struggling for the past 3 hours to get it to work in a loop.
A=5E-6; % amplitude
Freq=20000;
w=Freq*2*pi; % angular frequency
Th_D=(0:1:360);
th=(Th_D .* (pi/180)); % phase angle radian
t=[0:2E-7:7.2E-5]; % time
for k=1:length(th)
Vt=-A*w;
Veff(k,:)=Vt.*sin(w.*t + th(k)); % Horn tip velocity
Vx=Veff(:,2);
Ue=Vx;
Uf=0;
Meff=10;
Mfr=20;
syms Ve Vf
B(k)=solve(Meff.*Ue(:,k) + Mfr*Uf==Meff*Ve + Mfr*Vf,...
Meff.*Ue(:,k).^2 + Mfr*Uf^2==Meff*Ve^2 + Mfr*Vf^2);
B1(k)=B(k).Ve; % effective mass output
B1_M(k)=double(B1);
B2(k)=B(k).Vf; % free mass output
B2_M(k)=double(B2);
end
Any help would be appreciated!!!

请先登录，再回答此问题。

回答（1 个）

Walter Roberson
Walter Roberson 2013-11-29
You have
Vx = Veff(:,2)
which selects a single column out of Veff and writes it to Vx, so Vx will be a single column.
You then have
Ue = Vx
so Ue will have a single column.
You then attempt to access Ue(:,k) . That can only work if k is 1: as soon as k gets to 2, you would be attempting to access column 2 of something that only has one column.

类别

在 Help Center 和 File Exchange 中查找有关 Loops and Conditional Statements 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by