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Re: solving equation system
From: |
Eric Chassande-Mottin |
Subject: |
Re: solving equation system |
Date: |
Tue, 19 Apr 2005 13:14:10 -0500 |
> I hope that someone can point out a shorter way to define the coefficient
> matrix since all its rows are of the form [1,x,x^2,x^3,x^4].
here, a is a vandermonde matrix
a=vander([124.5 111 88.9 75.5 63]);
octave:1> a=vander([124.5 111 88.9 75.5 63])
a =
2.4026e+08 1.9298e+06 1.5500e+04 1.2450e+02 1.0000e+00
1.5181e+08 1.3676e+06 1.2321e+04 1.1100e+02 1.0000e+00
6.2461e+07 7.0260e+05 7.9032e+03 8.8900e+01 1.0000e+00
3.2493e+07 4.3037e+05 5.7002e+03 7.5500e+01 1.0000e+00
1.5753e+07 2.5005e+05 3.9690e+03 6.3000e+01 1.0000e+00
you need to flip it to choose the same coordinate system as you did:
a=fliplr(a);
> octave:6>
> a=[1,124.5,124.5^2,124.5^3,124.5^4;1,111,111^2,111^3,111^4;1,88.9,88.9^2,88.9^3,88.9^4;1,75.5,75.5^2,75.5^3,75.5^4;1,63,63^2,63^3,63^4]
> a =
>
> 1.0000e+00 1.2450e+02 1.5500e+04 1.9298e+06 2.4026e+08
> 1.0000e+00 1.1100e+02 1.2321e+04 1.3676e+06 1.5181e+08
> 1.0000e+00 8.8900e+01 7.9032e+03 7.0260e+05 6.2461e+07
> 1.0000e+00 7.5500e+01 5.7002e+03 4.3037e+05 3.2493e+07
> 1.0000e+00 6.3000e+01 3.9690e+03 2.5005e+05 1.5753e+07
eric.
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