modelling master equation- Need help

[ptc-2676882]

Hi ! Need some help on modelling stuff

Say I have two equations with simple polynomial form

Y1 = a1 X^2 + b1X +C1 at 50deg C

Y2 = a2 X^2 + b2X +C2 at 100deg C

I need to model a master equation that can predict any equation between 50C and 100C

Say what for example what will be the new equation at 55C based on above two equations. That means we need to predict any equation( at specified temperature) with these two equations as boundary conditions.

Any suggestions ?

[MikeArmstrong]

Could you not use pspline and interpolate between?

Mike

[wayne · Accepted solution]

As Mike suggested, you can interpolate (only linear though, unless you have some other criteria)

[ptc-2676882]

Thanks Wayne, the approach what you have presented is quite helpful.

Cheers

[Fred_Kohlhepp]

yes you can

[RichardJ]

You guys beat me to it. The only possibility is linear interpolation, but I would do the interpolation in K, not C. There's no way to know whether it's actually linear in eoither unit, but I would argue that if it's linear at all then it's more ilkely to be linear in K.

[Fred_Kohlhepp]

Whether it's K, C, F, or R; it's fifty units wide. the "linterp" function does slope and intercept. I expect (haven't checked) that the linear interpolation would deliver the same results.

[RichardJ]

I expect (haven't checked) that the linear interpolation would deliver the same results.

True. Very close anyway. It's that physicist in me shuddering when C is used for anything other than the weather

[ptc-2676882]

Richard Thanks for bringing up the issue of C or K. Although it doesn't effect my program , your question has made me a realize that it could be a potential issue if the relation is not linear and if there are many other parameters included in the model.

Thanks guys for all your feed back

[ptc-2676882]

Fred, Thanks once again for your quick response and rescue. In additions to what Wayne has suggested, your answers was also quite helpful in a different approach.

Cheers

[ValeryOchkov]

I have some problem - two functions of density-concentration of HCl at 15C and 20C.

Use please my Mathcad Server:

http://twtmas.mpei.ac.ru/mas/worksheets/C_HCl_t.mcd

and download the Mathcad 15 function:

http://twt.mpei.ac.ru/TTHB/1/Water-chem/functions/C_HCL_t.xmcdz