Non-linear equation solution

[battler.]

I have used Lev-Mar Non-Linear VI before but cannot understand how to apply to the following:

deltaTC = R(TC)*L^2 + QS + QC(TC) +QR(TC)*dt

where variables containing (TC) are dependent on TC.

I have samples of change of L over time (dt).  Trying to determine dTC with variables dependent on TC (current value - which means initial T + dTC).

Any help much appreciated.

[altenbach]

Can you show us some typica data?

What terms are fixed? What are the fitting parameters? What is the difference between "T" and "TC"

So "L" is "y" and you should solve your equation for L to make a model, right?

[battler.]

Hi altenbach,

Tc = current temperature

T = initial temperature

As shown below, a step change in L (y) results in a temperature change up to new steady-state temperature.

I need to model this temperature change function.

[Edna-S]

Hi Battler,

I am not sure if you know this or not but Lev-Mar Non-Linear VI is not supported any more. Instead you can use Nonlinear Curve Fit.vi . It is located in function->mathematics->fitting palette.

The functionality of both of them is the same.Next you can go LabVIEW help, search for this VI, and then look at the "Linear, Exp, and Power Fitting VI: labview\examples\math\curvefit.llb"

example. On the block diagram go to "Time out"and "true" for the case structures.You will see the Nonlinear Curve fit.vi, you need to input your equation to the reference terminal f(x,a). So

you need to make a subVI of your equation, and input it into f(x,a). Hope this helps!!

Edna