Prev: sym,cell
Next: modem to pc interface using matlab
From: Dan Blakeley on 29 Jul 2010 09:27

Hi all!
Have a problem on coursework and desperately need help.
I have 2 equation which need fitting to data of the form

aX+(Z+X+Y)(c+Y)=0
dY=(Z+X+Y)(e+X)=0.

I have 10 data points for variable X and Z and I know all paramters except d. I also do not know data points for variable Y.

How can I use optimization to find possible parameter estimates of d?
I do not need to know any data from variable Y.

Any help anybody could give me would be greatly appreciated!

Regards

Dan
From: John D'Errico on 29 Jul 2010 10:28
"Dan Blakeley" <daniel.blakeley(a)hotmail.co.uk> wrote in message <i2rvjq$fhb$1(a)fred.mathworks.com>...
>
> Hi all!
> Have a problem on coursework and desperately need help.
> I have 2 equation which need fitting to data of the form
>
> aX+(Z+X+Y)(c+Y)=0
> dY=(Z+X+Y)(e+X)=0.
>
> I have 10 data points for variable X and Z and I know all paramters except d. I also do not know data points for variable Y.
>
> How can I use optimization to find possible parameter estimates of d?
> I do not need to know any data from variable Y.

So you have no idea what the value of Y is,
but it takes on an unknown value for each data
point?

I suppose for each data point, you could solve
for the value of Y from the first equation, but it is
quadratic in Y, so there are zero, one, or two
solutions possible for every data point.

aX+(Z+X+Y)(c+Y)=0

Once you have those values, it is trivial to compute
the scalar d that satisfies the second expression, at
least IF you knew which of the solutions in Y to
choose.

I assume that the second equation is actually

dY + (Z+X+Y)(e+X)=0

John
 | 
Pages: 1
Prev: sym,cell
Next: modem to pc interface using matlab