cartesian to polar?

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katerina jablonski
i have tried to turn my values into polar (I need the angle of Ztot) but it's giving me the wrong value. where is my error?
C1Z = -1/(w*C1*1i);
C2Z = -1/(w*C2*1i);
LZ = w*L*1i;
Ztot = 1/((1/(C1R + C1Z)) + (1/(C2R + C2Z)) + (1/(LZ + Rw +Rsns)));
mag = abs(Ztot);
theta = (angle(Ztot));
real = mag;
imag = theta;
[th,r] = cart2pol (real,imag);
  1 个评论
Sean de Wolski
Sean de Wolski 2012-6-5
don't overwrite the very useful builtin functions real() and imag()

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回答（3 个）

Walter Roberson
Walter Roberson 2012-6-5
You indicate that you need the angle of Ztot, but you seem to already be calculating that and placing it in theta. And then you are using that angle as if it was a cartesian coordinate ?? Your calculations look to me more like you have polar coordinates that you want to translate to cartesian ?
katerina jablonski
right, you can see that i'm not sure how to use these commands. we haven't been taught how to use matlab, so i'm trying to do this with no instruction. what is my best course to show the polar angle of Ztot? i don't know what to use or not use, and how to use it!
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Walter Roberson
Walter Roberson 2012-6-5
You can display values to the command window using disp() or fprintf(). You can display simple messages "pop-up" using msgdlg() and related functions. You can display text data in a user interface control area using uicontrol() or uitable(). You can display text data in a graphic drawing area using text(). You can plot lines in a graphic drawing area using plot() or line(). You can plot a polar coordinate graph in a graphic drawing area using polar()

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katerina jablonski
okay here's what i ended up doing. it seems okay. any suggestions to make it better?
Ztot = ((1/(C1R + C1Z)) + (1/(C2R + C2Z)) + (1/(Rw + Rsns + LZ)))^(-1);
real = abs(Ztot)
imag = (angle(Ztot))*(180/pi)
theta = cosd(imag)
  2 个评论
Honglei Chen
Honglei Chen 2012-6-5
I don't quite get your question. You said you need the angle of Ztot, why isn't it just angle(Ztot)?
Walter Roberson
Walter Roberson 2012-6-5
Ztot = ((1/(C1R + C1Z)) + (1/(C2R + C2Z)) + (1/(Rw + Rsns + LZ)))^(-1);
Zmag = abs(Ztot);
Zangle = angle(Ztot); %This is the angle in radians
Zdeg = Zangle * 180/pi; %and in degrees if you need that
Zcos = cos(Zangle); %cos of angle, not angle itself

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