| /*************************************************************************/ |
| /* */ |
| /* Copyright (c) 1994 Stanford University */ |
| /* */ |
| /* All rights reserved. */ |
| /* */ |
| /* Permission is given to use, copy, and modify this software for any */ |
| /* non-commercial purpose as long as this copyright notice is not */ |
| /* removed. All other uses, including redistribution in whole or in */ |
| /* part, are forbidden without prior written permission. */ |
| /* */ |
| /* This software is provided with absolutely no warranty and no */ |
| /* support. */ |
| /* */ |
| /*************************************************************************/ |
| |
| EXTERN_ENV |
| #include <math.h> |
| #include "global.h" |
| |
| /* return the value of a with the same sign as b */ |
| |
| #define sign(a,b) (b < 0 ) ? ( (a < 0) ? a : -a) : ( (a < 0) ? -a : a) |
| |
| /* compute some relevant distances between the two input molecules to |
| this routine. if they are greater than the cutoff radius, compute |
| these distances as if one of the particles were at its mirror image |
| (periodic boundary conditions). |
| used by the intermolecular interactions routines */ |
| inline void CSHIFT(double *XA, double *XB, double XMA, double XMB, double *XL, double BOXH, double BOXL) |
| { |
| |
| int I; |
| |
| XL[0] = XMA-XMB; |
| XL[1] = XMA-XB[0]; |
| XL[2] = XMA-XB[2]; |
| XL[3] = XA[0]-XMB; |
| XL[4] = XA[2]-XMB; |
| XL[5] = XA[0]-XB[0]; |
| XL[6] = XA[0]-XB[2]; |
| XL[7] = XA[2]-XB[0]; |
| XL[8] = XA[2]-XB[2]; |
| XL[9] = XA[1]-XB[1]; |
| XL[10] = XA[1]-XB[0]; |
| XL[11] = XA[1]-XB[2]; |
| XL[12] = XA[0]-XB[1]; |
| XL[13] = XA[2]-XB[1]; |
| |
| #pragma novector |
| /* go through all 14 distances computed */ |
| for (I = 0; I < 14; I++) { |
| /* if the value is greater than the cutoff radius */ |
| if (fabs(XL[I]) > BOXH) { |
| XL[I] = XL[I] -(sign(BOXL,XL[I])); |
| } |
| } /* for */ |
| } /* end of subroutine CSHIFT */ |
| |
