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/*************************************************************************
* *
* Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith. *
* All rights reserved. Email: russ@q12.org Web: www.q12.org *
* *
* This library is free software; you can redistribute it and/or *
* modify it under the terms of *
* The BSD-style license that is included with this library in *
* the file LICENSE-BSD.TXT. *
* *
* This library is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files *
* LICENSE.TXT and LICENSE-BSD.TXT for more details. *
* *
*************************************************************************/
/*
given (A,b,lo,hi), solve the LCP problem: A*x = b+w, where each x(i),w(i)
satisfies one of
(1) x = lo, w >= 0
(2) x = hi, w <= 0
(3) lo < x < hi, w = 0
A is a matrix of dimension n*n, everything else is a vector of size n*1.
lo and hi can be +/- dInfinity as needed. the first `nub' variables are
unbounded, i.e. hi and lo are assumed to be +/- dInfinity.
we restrict lo(i) <= 0 and hi(i) >= 0.
the original data (A,b) may be modified by this function.
if the `findex' (friction index) parameter is nonzero, it points to an array
of index values. in this case constraints that have findex[i] >= 0 are
special. all non-special constraints are solved for, then the lo and hi values
for the special constraints are set:
hi[i] = abs( hi[i] * x[findex[i]] )
lo[i] = -hi[i]
and the solution continues. this mechanism allows a friction approximation
to be implemented. the first `nub' variables are assumed to have findex < 0.
*/
#ifndef _BT_LCP_H_
#define _BT_LCP_H_
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include "LinearMath/btScalar.h"
#include "LinearMath/btAlignedObjectArray.h"
struct btDantzigScratchMemory
{
btAlignedObjectArray<btScalar> m_scratch;
btAlignedObjectArray<btScalar> L;
btAlignedObjectArray<btScalar> d;
btAlignedObjectArray<btScalar> delta_w;
btAlignedObjectArray<btScalar> delta_x;
btAlignedObjectArray<btScalar> Dell;
btAlignedObjectArray<btScalar> ell;
btAlignedObjectArray<btScalar *> Arows;
btAlignedObjectArray<int> p;
btAlignedObjectArray<int> C;
btAlignedObjectArray<bool> state;
};
//return false if solving failed
bool btSolveDantzigLCP(int n, btScalar *A, btScalar *x, btScalar *b, btScalar *w,
int nub, btScalar *lo, btScalar *hi, int *findex, btDantzigScratchMemory &scratch);
#endif //_BT_LCP_H_
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