kupdatemd.br

/* -------------------------------------------------------------------------- *
 *                                   OpenMM                                   *
 * -------------------------------------------------------------------------- *
 * This is part of the OpenMM molecular simulation toolkit originating from   *
 * Simbios, the NIH National Center for Physics-Based Simulation of           *
 * Biological Structures at Stanford, funded under the NIH Roadmap for        *
 * Medical Research, grant U54 GM072970. See https://simtk.org.               *
 *                                                                            *
 * Portions copyright (c) 2008 Stanford University and the Authors.           *
 * Authors: Peter Eastman, Mark Friedrichs, Chris Bruns                       *
 * Contributors:                                                              *
 *                                                                            *
 * Permission is hereby granted, free of charge, to any person obtaining a    *
 * copy of this software and associated documentation files (the "Software"), *
 * to deal in the Software without restriction, including without limitation  *
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,   *
 * and/or sell copies of the Software, and to permit persons to whom the      *
 * Software is furnished to do so, subject to the following conditions:       *
 *                                                                            *
 * The above copyright notice and this permission notice shall be included in *
 * all copies or substantial portions of the Software.                        *
 *                                                                            *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,   *
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL    *
 * THE AUTHORS, CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,    *
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR      *
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE  *
 * USE OR OTHER DEALINGS IN THE SOFTWARE.                                     *
 * -------------------------------------------------------------------------- */

kernel void kupdate_md1( 
		float dt,
		float3 posq<>, 
		float3 v<>, 
		float3 f<>,
		float invmass<>,
		out float3 posqp<> ){

   posqp  = v + dt*invmass*f;
	posqp *= dt;
}

kernel void kupdate_md2(
		float dtinv, //1/dt
		float3 posqp<>, //positions after constraints
		float3 posq<>,  //positions before update
		out float3 vnew<>, //Corrected velocities
		out float3 posqnew<> //equal to posqp, avoids an extra call to copy
		){
   vnew        = posqp * dtinv;
   posqnew     = posq  + posqp;
}

kernel void kupdateMdNoShake(
      float dt,
      float3 posq<>,
      float3 v<>, 
      float3 f<>,
      float invmass<>,
      out float3 outv<>,
      out float3 posqp<> ){
   posqp     = posq;
   outv      = v + dt*invmass*f;
   posqp    += dt*outv;
}