How can I solve this problem by using Gauss elimination method? Thanks alot!

3x+ y -5z -w=0

-2x +4y +z -2w= 2

2x+ 2y -3z +5w= 7

-3x +2y -z +4w=6

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- Sep 23rd 2013, 06:13 AMmath88Gauss elimination method
How can I solve this problem by using Gauss elimination method? Thanks alot!

3x+ y -5z -w=0

-2x +4y +z -2w= 2

2x+ 2y -3z +5w= 7

-3x +2y -z +4w=6 - Sep 23rd 2013, 06:47 AMPlatoRe: Gauss elimination method
Have a look at this webpage.

- Sep 24th 2013, 03:14 AMmath88Re: Gauss elimination method
Thank you. The webpage is very helpful.

- Sep 24th 2013, 03:22 AMPlatoRe: Gauss elimination method
- Nov 11th 2013, 04:45 AMElamkumaranRe: Gauss elimination method
Hi,

I have following bivariate data.

(y) 800 1000 1200

(x)

1150 1380.4 1500.2 1614.5

1200 1377.7 1499.0 1613.6

1250 1375.2 1497.1 1612.6

The correct solution for this interms of bivariate equation (a+bx+cy+dx^2+ey^2+fxy)

914.033 - 0.0205000x + 0.645500y - 0.000040000x^2 - 0.000077500y^2 + 0.000082500xy.

But when i use matlab c=inv(A) * b, i get coefficient which produces more errors. What i am looking for is high accuracy interms of 0.5 error or less than that. Is there any other way i can calculate the coefficients? pls suggest. - Nov 11th 2013, 06:29 AMElamkumaranRe: Gauss elimination method
Hi,

I have following bivariate data.

(y) 800 1000 1200

(x)

1150 1380.4 1500.2 1614.5

1200 1377.7 1499.0 1613.6

1250 1375.2 1497.1 1612.6

The correct solution for this in terms of bi-variate equation (a+bx+cy+dx^2+ey^2+fxy)

914.033 - 0.0205000x + 0.645500y - 0.000040000x^2 - 0.000077500y^2 + 0.000082500xy.

But when i use matlab c=inv(A) * b, i get coefficient which produces more errors. Following are the coefficient produced by matlab

a = -8.12E+03

1.52E+01

4.61E-01

-6.46E-03

-8.56E-05

2.50E-04

What i am looking for is high accuracy in terms of 0.5 error or less than that. Is there any other way/tool i can calculate the coefficients with very high accuracy? pls suggest.

matlab code:

a=[9 10800 9000 12975000 9240000 10800000

10800 12975000 10800000 15606000000 11088000000 12975000000

9000 10800000 9240000 12975000000 9720000000 11088000000

12975000 15606000000 12975000000 18792000000000 13321000000000 15606000000000

9240000 11088000000 9720000000 13321000000000 10450000000000 11664000000000

10800000 12975000000 11088000000 15606000000000 11664000000000 13321000000000];

b = [13470.3

16163800

13611800

19418500000

14112200000

16333700000];

ans = inv(a)*b