Open Dynamics Engine

lcp.h

00001 /*************************************************************************
00002  *                                                                       *
00003  * Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith.       *
00004  * All rights reserved.  Email: russ@q12.org   Web: www.q12.org          *
00005  *                                                                       *
00006  * This library is free software; you can redistribute it and/or         *
00007  * modify it under the terms of EITHER:                                  *
00008  *   (1) The GNU Lesser General Public License as published by the Free  *
00009  *       Software Foundation; either version 2.1 of the License, or (at  *
00010  *       your option) any later version. The text of the GNU Lesser      *
00011  *       General Public License is included with this library in the     *
00012  *       file LICENSE.TXT.                                               *
00013  *   (2) The BSD-style license that is included with this library in     *
00014  *       the file LICENSE-BSD.TXT.                                       *
00015  *                                                                       *
00016  * This library is distributed in the hope that it will be useful,       *
00017  * but WITHOUT ANY WARRANTY; without even the implied warranty of        *
00018  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files    *
00019  * LICENSE.TXT and LICENSE-BSD.TXT for more details.                     *
00020  *                                                                       *
00021  *************************************************************************/
00022 
00023 /*
00024 
00025 given (A,b,lo,hi), solve the LCP problem: A*x = b+w, where each x(i),w(i)
00026 satisfies one of
00027    (1) x = lo, w >= 0
00028    (2) x = hi, w <= 0
00029    (3) lo < x < hi, w = 0
00030 A is a matrix of dimension n*n, everything else is a vector of size n*1.
00031 lo and hi can be +/- dInfinity as needed. the first `nub' variables are
00032 unbounded, i.e. hi and lo are assumed to be +/- dInfinity.
00033 
00034 we restrict lo(i) <= 0 and hi(i) >= 0.
00035 
00036 the original data (A,b) may be modified by this function.
00037 
00038 if the `findex' (friction index) parameter is nonzero, it points to an array
00039 of index values. in this case constraints that have findex[i] >= 0 are
00040 special. all non-special constraints are solved for, then the lo and hi values
00041 for the special constraints are set:
00042   hi[i] = abs( hi[i] * x[findex[i]] )
00043   lo[i] = -hi[i]
00044 and the solution continues. this mechanism allows a friction approximation
00045 to be implemented. the first `nub' variables are assumed to have findex < 0.
00046 
00047 */
00048 
00049 
00050 #ifndef _ODE_LCP_H_
00051 #define _ODE_LCP_H_
00052 
00053 class dxWorldProcessMemArena;
00054 
00055 void dSolveLCP (dxWorldProcessMemArena *memarena, 
00056   int n, dReal *A, dReal *x, dReal *b, dReal *w,
00057    int nub, dReal *lo, dReal *hi, int *findex);
00058 
00059 size_t dEstimateSolveLCPMemoryReq(int n, bool outer_w_avail);
00060 
00061 #endif