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qiushidaren

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Plot I-V Curve by Using Matlab
Nov 19^th, 2006, 7:40pm

Hi all, I want to plot an i-v curve of this equation i=100*[1.3-v+500*(5-i)]^2 by using Matlab, but unfortunately it looks that the plot I get isn�t the one that I want, so I think there must be something wrong but I don�t know it. Your suggestions and comments will be highly appreciated!
Here is my code:
Quote:

%current versus voltage curve
v=0:0.1:3;
i=100*[1.3-v+500*(5-i)].^2;
plot(v,i)
title('current versus voltage of 2.6(c)')
xlabel('Voltage(V)')
ylabel('Current(uA)')
grid

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Geoffrey_Coram Senior Fellow Offline Posts: 1998 Massachusetts, USA	Re: Plot I-V Curve by Using Matlab Reply #1 - Nov 20^th, 2006, 4:30am qiushidaren wrote on Nov 19^th, 2006, 7:40pm: i=100[1.3-v+500(5-i)]^2 That's an implicit equation, because "i" appears on both sides. I expect you need to solve the quadratic equation so you get an explicit equation, i = function only of v and constants.
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qiushidaren

Community Member

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I am a lovely
MOSFET!

Posts: 86
Chengdu

Re: Plot I-V Curve by Using Matlab
Reply #2 - Nov 20^th, 2006, 4:40am

Geoffrey_Coram wrote on Nov 20^th, 2006, 4:30am:

qiushidaren wrote on Nov 19^th, 2006, 7:40pm:

i=100*[1.3-v+500*(5-i)]^2

That's an implicit equation, because "i" appears on both sides. I expect you need to solve the quadratic equation so you get an explicit equation, i = function only of v and constants.

Yes, it is an implicit equation, you know sometimes we can't get an explicit equation, or we don't need to solve it to be an explicit one, so I want to know how can I get the correct plot of this kind of implicit equation, thank you in advance!

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Geoffrey_Coram Senior Fellow Offline Posts: 1998 Massachusetts, USA	Re: Plot I-V Curve by Using Matlab Reply #3 - Nov 20^th, 2006, 7:42am Top result from a Google search "matlab implicit plot": http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=300&obj...
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mg777 Senior Member Offline Posts: 131	Re: Plot I-V Curve by Using Matlab Reply #4 - Jan 15^th, 2007, 12:20pm Besides you're lucky to have a simple quadratic equation. Solve it by hand! M.G.Rajan www.eecalc.com
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