Thread Subject:

coefficient

P=Z(1)+Z(2)*A+Z(3)*B+Z(4)*C+Z(5)*D+Z(6)*E+Z(7)*F

WITH:
_____________________________________________________________________
 
P A B C D E F
_____________________________________________________________________
 -10881.5560 -0.2792 -0.0519 0.1807 -0.2098 0.1945 -0.1630
 
    -7409.7713 0.0188 -0.2591 0.2497 -0.1827 0.1191 -0.0729
    
    -5520.5733 0.1820 -0.3162 0.2282 -0.1338 0.0712 -0.0359
  
    -4229.9591 0.2916 -0.3320 0.1986 -0.0991 0.0452 -0.0196


my problem is how can I find the coefficient : Z(1),Z(2),Z(3),Z(4),Z(5),Z(6),Z(7)

On 23 Mrz., 12:35, "nouha " <no...@voila.fr> wrote:
> P=Z(1)+Z(2)*A+Z(3)*B+Z(4)*C+Z(5)*D+Z(6)*E+Z(7)*F
>
> WITH:
> _____________________________________________________________________
>
> P                      A                B               C            D             E            F
> _____________________________________________________________________
>  -10881.5560    -0.2792    -0.0519     0.1807    -0.2098     0.1945    -0.1630    
>
>     -7409.7713     0.0188    -0.2591     0.2497    -0.1827     0.1191    -0.0729    
>
>     -5520.5733     0.1820    -0.3162     0.2282    -0.1338     0.0712    -0.0359    
>
>     -4229.9591     0.2916    -0.3320     0.1986    -0.0991     0.0452    -0.0196        
>
> my problem is how can I find the coefficient  :  Z(1),Z(2),Z(3),Z(4),Z(5),Z(6),Z(7)

Trying to estimate 7 coefficients with 4 measurement data does not
make much sense...
But anyway:
You could set Z(5)=Z(6)=Z(7)=0 and solve the linear system
P_i = Z(1) + Z(2)*A_i + Z(3)*B_i + Z(4)*C_i (i=1,..,4)
in Z(1),Z(2),Z(3) and Z(4).

Best wishes
Torsten.

"nouha " <nouha@voila.fr> wrote in message
news:imclt8$gv7$1@fred.mathworks.com...
>
> P=Z(1)+Z(2)*A+Z(3)*B+Z(4)*C+Z(5)*D+Z(6)*E+Z(7)*F
>
> WITH:
> _____________________________________________________________________
>
> P A B C D
> E F
> _____________________________________________________________________
> -10881.5560 -0.2792 -0.0519 0.1807 -0.2098
> 0.1945 -0.1630
> -7409.7713 0.0188 -0.2591 0.2497 -0.1827
> 0.1191 -0.0729 -5520.5733 0.1820 -0.3162
> 0.2282 -0.1338 0.0712 -0.0359 -4229.9591
> 0.2916 -0.3320 0.1986 -0.0991 0.0452 -0.0196
>
> my problem is how can I find the coefficient :
> Z(1),Z(2),Z(3),Z(4),Z(5),Z(6),Z(7)

1) Obtain more data. Using four sets of data to determine seven coefficients
means this is an underdetermined problem; there may be multiple solutions.

2) Read through the Regression Analysis section of the documentation for a
description of some of the commands you can use for this task and decide
which best suits your needs:

http://www.mathworks.com/help/techdoc/data_analysis/f1-6010.html

--
Steve Lord
slord@mathworks.com
To contact Technical Support use the Contact Us link on
http://www.mathworks.com