Error on if loop

Question

Emily Gobreski 2016-6-17

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/290413-error-on-if-loop

评论： Star Strider 2016-6-17

if 0<theta<180, x=C*A
else xx=CC*AA
end
Undefined function or variable 'A'.
Error in DynamicsProject (line 60)
if 0<theta<180, x=C*A

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Answer 1

Star Strider 2016-6-17

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/290413-error-on-if-loop#answer_225781

在 MATLAB Online 中打开

It is asking you to define variable ‘A’.

That aside, the if condition should be defined as:

if (0 < theta) & (theta < 180)

There is not enough information presented to allow a more detailed Answer.

There’s quite likely a more efficient way to do what you want to do, if we have the necessary information to help you do it.

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Emily Gobreski 2016-6-17

编辑：Star Strider 2016-6-17

在 MATLAB Online 中打开

Thank you for your help. I have included the rest of my code. (I keep getting scolded for posting it so i was trying to be concise)

theta=30
  sign=(cosd (theta)/abs (cosd (theta)))
  u=.8
  w=(2*pi/5)
  R=1
  c=4.05/12
  H=18/12
  y=H-(R*sind(theta/2))
  Md=50/32.2
  Id=(.5*Md*R^2)
  Mp=75/32.2
  Mb=30/32.2
  alpha=0
  u=.8
  L=(6/12*R)
  g=32.2
  ax=(-R*w^2)*cosd(theta)
  ab=(-R*w^2*cosd(theta))-(R*w^2*sind(theta))
  ay=(-R*w^2)*sind(theta)
    a=[1 0 1 0 0 0 0 0 0 0 0; 0 1 0 1 0 0 0 0 0 0 0; 0 0 -R*sind(theta) R*cosd(theta) 0 0 0 0 0 0 1; 0 0 0 0 1 0 1 0 0 0 0; 0 0 0 0 0 1 0 1 0 0 0; 0 0 0 0 -R*sind(theta) R*cosd(theta) 0 0 0 0 0; 0 0 -1 0 -1 0 0 0 (4*abs(sign)) 0 0; 0 0 0 -1 0 -1 0 0 (-4*u*sign) 0 0; 0 0 -c (3*R) -c  (-3*R) 0 0 (-4*(y-c)) 0 0; 0 0 0 0 0 0 0 0 -sign u*sign 0; 0 0 0 0 0 0 0 0 (-u*sign) 1 0]
    C=[0 Md*g Id*alpha 0 Md*g Id*alpha Mp*ax Mp*ay+Mp*g 0 Mb*ab Mb*g]
    x=C/inv(a)
    theta=120
    sign=(cosd (theta)/abs (cosd (theta)))
    u=.8
    w=(2*pi/5)
    R=1
    c=4.05/12
    H=18/12
    y=H-(R*sind(theta/2))
    Md=50/32.2
    Id=(.5*Md*R^2)
    Mp=75/32.2
    Mb=30/32.2
    alpha=0
    u=.8
    L=(6/12*R)
    g=32.2
    ax=(-R*w^2)*cosd(theta)
    ab=(-R*w^2*cosd(theta))-(R*w^2*sind(theta))
    ay=(-R*w^2)*sind(theta)
    AA=[1 0 1 0 0 0 0 0 0; 0 1 0 1 0 0 0 0 0; 0 0 -R*sind(theta) R*cosd(theta) 0 0 0 0 0; 0 0 0 0 1 0 1 0 0; 0 0 0 0 0 1 0 1 0; 0 0 -1 0 -1 0 0 0 0; 0 0 -c 3*R -c -3*R 0 0 0; 0 0 0 0 0 0 0 0 0; 0 0 0 0 0 0 0 0 0]
    CC=[0 Md*g Id*alpha 0 Md*g Id*alpha Mp*ax Mp*ay+Mp*g Mb*g]
    xx=CC*AA
    if 0<theta<180, x=C*A
    else xx=CC*AA
    end

Emily Gobreski 2016-6-17

It works! thank you so much!

Star Strider 2016-6-17

My pleasure!

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Error on if loop

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