Plot function and Interpolate Plz Help!!!!

[lil_zu]

Im trying to obtain a plot from  the following function ( see attached file)  a I-V curve and then from the plot i wanna determine values for "I" when  values of V are specified. I wanna do this without using cursers but programmatically.(possibly using interpolate functions) .. I hope someone can help me..thanks a lot

[Hillary_C_E]

Hi lil_zu,

What you are going to want to do is create the equation inside a for loop. Use a feedback node by wiring the output of your equation back to where you input the value for "I". Have the loop iterate the number of times you want it to run. Take the outputs for V and I in the form of arrays. Bundle the arrays and put them into an XY graph.

Let us know how it goes!

[altenbach]

Well, first you need to solve for either I or V.

If this is not possible (I haven't really tried), you could inplement a simple newton-raphson iteration to solve for I for any given voltage.

Simply find I by solving "function(I,V) - I = 0" after picking a V.

[lil_zu]

Im still a bit confused about this..how do i solve it in Labview? .is it possible to plot this function without solving?

[lil_zu]

guys any ideas? coz im really stuck :(..plz help

[lil_zu]

and how do i itereate a for loop  to create graph for steps of 0.1 coz the range for is roughly about 0 to 1 in very small steps

[altenbach]

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lil_zu wrote:
...is it possible to plot this function without solving?

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No! 😮 You cannot plot a function unless you can solve it (either analytically or numerically). 😉

Do you have an image of how it is supposed to look like?

What are typical ranges for I and V?

Do you have a link to a website that explains your application?

[altenbach]

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lil_zu wrote:
and how do i itereate a for loop  to create graph for steps of 0.1 coz the range for is roughly about 0 to 1 in very small steps

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I guess you are talking avout interpolation, not iteration. There are several interpolation routines in the math subpalette, check the online help. If linear interpolation is sufficient, you can use "interpolate array" from the array palette.

[Hillary_C_E]

So, you can graph this equation without solving for I or V. You'll just use a Feedback Node for the value of I and iterate the loop with the equation for a given number of times. I found for this equation after about 4 times, the value wasn't changing. I've set it to be 10 to ensure that the value is reaching its limit before plotting it. I've attached a screenshot.

[BruceMoyer]

I guess this is the beauty of the Internet.  You can post questions wherever you want and then just select the best answer to turn in for your homework.

http://forums.lavag.org/Plot-function-and-Interpolate-Plz-Help-t10486.html