[Boost-users] Re: There's someone using boost lu_substitute?

From: Angus Leeming (angus.leeming_at_[hidden])
Date: 2004-09-02 06:07:31

yanyaqin wrote:

> Hi folks,
> I'm ready to use boost lu_substitute for solving sparse symmetric linear
> equation, but the document for lu.hpp is almost none. Is there someone
> could provide me a real number demo?
>  
> Best regards!
> Yan Yaqin 2004-09-02

Hi, Yan Yaqin

attached is a simple example that use lu_substitute et al to calculate the
length of each spring in a system of 10 springs arranged in series:

        |------o------o--- ~ ---o------o------|

where each spring has a random stiffness in the range 0.8 <= k <= 1.2

$ g++ -I$HOME/boost/1_31_0 -o mesh mesh.cpp
$ ./mesh
Node[0] position: 0
Node[1] position: 0.864606, element length: 0.864606
Node[2] position: 1.93203, element length: 1.06742
Node[3] position: 3.14607, element length: 1.21404
Node[4] position: 4.03935, element length: 0.893288
Node[5] position: 5.02106, element length: 0.981706
Node[6] position: 5.96605, element length: 0.94499
Node[7] position: 6.95916, element length: 0.993113
Node[8] position: 8.02025, element length: 1.06109
Node[9] position: 9, element length: 0.979749

Note that the code doesn't run when compiled against current Boost CVS
because of a bug introduced to the Ublas library yesterday.

Regards,
Angus