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Commit 039bb3fb authored by Peter Eastman's avatar Peter Eastman
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Very minor code simplification

parent 70ff98db
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platforms/cuda/src/kernels/coulombLennardJones.cu
View file @ 039bb3fb
#if USE_EWALD #if USE_EWALD
bool needCorrection = hasExclusions && isExcluded && atom1 != atom2 && atom1 < NUM_ATOMS && atom2 < NUM_ATOMS; bool needCorrection = hasExclusions && isExcluded && atom1 != atom2 && atom1 < NUM_ATOMS && atom2 < NUM_ATOMS;
if (!isExcluded || needCorrection) { if ((!isExcluded && r2 < CUTOFF_SQUARED) || needCorrection) {
if (r2 < CUTOFF_SQUARED || needCorrection) { const real alphaR = EWALD_ALPHA*r;
const real alphaR = EWALD_ALPHA*r; const real expAlphaRSqr = EXP(-alphaR*alphaR);
const real expAlphaRSqr = EXP(-alphaR*alphaR); const real prefactor = 138.935456f*posq1.w*posq2.w*invR;
const real prefactor = 138.935456f*posq1.w*posq2.w*invR;
#ifdef USE_DOUBLE_PRECISION #ifdef USE_DOUBLE_PRECISION
const real erfcAlphaR = erfc(alphaR); const real erfcAlphaR = erfc(alphaR);
#else #else
// This approximation for erfc is from Abramowitz and Stegun (1964) p. 299. They cite the following as // This approximation for erfc is from Abramowitz and Stegun (1964) p. 299. They cite the following as
// the original source: C. Hastings, Jr., Approximations for Digital Computers (1955). It has a maximum // the original source: C. Hastings, Jr., Approximations for Digital Computers (1955). It has a maximum
// error of 3e-7. // error of 3e-7.
real t = 1.0f+(0.0705230784f+(0.0422820123f+(0.0092705272f+(0.0001520143f+(0.0002765672f+0.0000430638f*alphaR)*alphaR)*alphaR)*alphaR)*alphaR)*alphaR; real t = 1.0f+(0.0705230784f+(0.0422820123f+(0.0092705272f+(0.0001520143f+(0.0002765672f+0.0000430638f*alphaR)*alphaR)*alphaR)*alphaR)*alphaR)*alphaR;
t *= t; t *= t;
t *= t; t *= t;
t *= t; t *= t;
const real erfcAlphaR = RECIP(t*t); const real erfcAlphaR = RECIP(t*t);
#endif #endif
real tempForce = 0.0f; real tempForce = 0.0f;
if (needCorrection) { if (needCorrection) {
// Subtract off the part of this interaction that was included in the reciprocal space contribution. // Subtract off the part of this interaction that was included in the reciprocal space contribution.
tempForce = -prefactor*((1.0f-erfcAlphaR)-alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI); tempForce = -prefactor*((1.0f-erfcAlphaR)-alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI);
tempEnergy += -prefactor*(1.0f-erfcAlphaR); tempEnergy += -prefactor*(1.0f-erfcAlphaR);
} }
else { else {
#if HAS_LENNARD_JONES #if HAS_LENNARD_JONES
real sig = sigmaEpsilon1.x + sigmaEpsilon2.x; real sig = sigmaEpsilon1.x + sigmaEpsilon2.x;
real sig2 = invR*sig; real sig2 = invR*sig;
sig2 *= sig2; sig2 *= sig2;
real sig6 = sig2*sig2*sig2; real sig6 = sig2*sig2*sig2;
real epssig6 = sig6*(sigmaEpsilon1.y*sigmaEpsilon2.y); real epssig6 = sig6*(sigmaEpsilon1.y*sigmaEpsilon2.y);
tempForce = epssig6*(12.0f*sig6 - 6.0f); tempForce = epssig6*(12.0f*sig6 - 6.0f);
real ljEnergy = epssig6*(sig6 - 1.0f); real ljEnergy = epssig6*(sig6 - 1.0f);
#if USE_LJ_SWITCH #if USE_LJ_SWITCH
if (r > LJ_SWITCH_CUTOFF) { if (r > LJ_SWITCH_CUTOFF) {
real x = r-LJ_SWITCH_CUTOFF; real x = r-LJ_SWITCH_CUTOFF;
real switchValue = 1+x*x*x*(LJ_SWITCH_C3+x*(LJ_SWITCH_C4+x*LJ_SWITCH_C5)); real switchValue = 1+x*x*x*(LJ_SWITCH_C3+x*(LJ_SWITCH_C4+x*LJ_SWITCH_C5));
real switchDeriv = x*x*(3*LJ_SWITCH_C3+x*(4*LJ_SWITCH_C4+x*5*LJ_SWITCH_C5)); real switchDeriv = x*x*(3*LJ_SWITCH_C3+x*(4*LJ_SWITCH_C4+x*5*LJ_SWITCH_C5));
tempForce = tempForce*switchValue - ljEnergy*switchDeriv*r; tempForce = tempForce*switchValue - ljEnergy*switchDeriv*r;
ljEnergy *= switchValue; ljEnergy *= switchValue;
} }
#endif #endif
tempForce += prefactor*(erfcAlphaR+alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI); tempForce += prefactor*(erfcAlphaR+alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI);
tempEnergy += ljEnergy + prefactor*erfcAlphaR; tempEnergy += ljEnergy + prefactor*erfcAlphaR;
#else #else
tempForce = prefactor*(erfcAlphaR+alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI); tempForce = prefactor*(erfcAlphaR+alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI);
tempEnergy += prefactor*erfcAlphaR; tempEnergy += prefactor*erfcAlphaR;
#endif #endif
}
dEdR += tempForce*invR*invR;
} }
dEdR += tempForce*invR*invR;
} }
#else #else
{ {
......
platforms/opencl/src/kernels/coulombLennardJones.cl
View file @ 039bb3fb
#if USE_EWALD #if USE_EWALD
bool needCorrection = hasExclusions && isExcluded && atom1 != atom2 && atom1 < NUM_ATOMS && atom2 < NUM_ATOMS; bool needCorrection = hasExclusions && isExcluded && atom1 != atom2 && atom1 < NUM_ATOMS && atom2 < NUM_ATOMS;
if (!isExcluded || needCorrection) { if ((!isExcluded && r2 < CUTOFF_SQUARED) || needCorrection) {
if (r2 < CUTOFF_SQUARED || needCorrection) { const real alphaR = EWALD_ALPHA*r;
const real alphaR = EWALD_ALPHA*r; const real expAlphaRSqr = EXP(-alphaR*alphaR);
const real expAlphaRSqr = EXP(-alphaR*alphaR); const real prefactor = 138.935456f*posq1.w*posq2.w*invR;
const real prefactor = 138.935456f*posq1.w*posq2.w*invR;
#ifdef USE_DOUBLE_PRECISION #ifdef USE_DOUBLE_PRECISION
const real erfcAlphaR = erfc(alphaR); const real erfcAlphaR = erfc(alphaR);
#else #else
// This approximation for erfc is from Abramowitz and Stegun (1964) p. 299. They cite the following as // This approximation for erfc is from Abramowitz and Stegun (1964) p. 299. They cite the following as
// the original source: C. Hastings, Jr., Approximations for Digital Computers (1955). It has a maximum // the original source: C. Hastings, Jr., Approximations for Digital Computers (1955). It has a maximum
// error of 3e-7. // error of 3e-7.
real t = 1.0f+(0.0705230784f+(0.0422820123f+(0.0092705272f+(0.0001520143f+(0.0002765672f+0.0000430638f*alphaR)*alphaR)*alphaR)*alphaR)*alphaR)*alphaR; real t = 1.0f+(0.0705230784f+(0.0422820123f+(0.0092705272f+(0.0001520143f+(0.0002765672f+0.0000430638f*alphaR)*alphaR)*alphaR)*alphaR)*alphaR)*alphaR;
t *= t; t *= t;
t *= t; t *= t;
t *= t; t *= t;
const real erfcAlphaR = RECIP(t*t); const real erfcAlphaR = RECIP(t*t);
#endif #endif
real tempForce = 0; real tempForce = 0;
if (needCorrection) { if (needCorrection) {
// Subtract off the part of this interaction that was included in the reciprocal space contribution. // Subtract off the part of this interaction that was included in the reciprocal space contribution.
tempForce = -prefactor*((1.0f-erfcAlphaR)-alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI); tempForce = -prefactor*((1.0f-erfcAlphaR)-alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI);
tempEnergy += -prefactor*(1.0f-erfcAlphaR); tempEnergy += -prefactor*(1.0f-erfcAlphaR);
} }
else { else {
#if HAS_LENNARD_JONES #if HAS_LENNARD_JONES
real sig = sigmaEpsilon1.x + sigmaEpsilon2.x; real sig = sigmaEpsilon1.x + sigmaEpsilon2.x;
real sig2 = invR*sig; real sig2 = invR*sig;
sig2 *= sig2; sig2 *= sig2;
real sig6 = sig2*sig2*sig2; real sig6 = sig2*sig2*sig2;
real epssig6 = sig6*(sigmaEpsilon1.y*sigmaEpsilon2.y); real epssig6 = sig6*(sigmaEpsilon1.y*sigmaEpsilon2.y);
tempForce = epssig6*(12.0f*sig6 - 6.0f); tempForce = epssig6*(12.0f*sig6 - 6.0f);
real ljEnergy = epssig6*(sig6 - 1.0f); real ljEnergy = epssig6*(sig6 - 1.0f);
#if USE_LJ_SWITCH #if USE_LJ_SWITCH
if (r > LJ_SWITCH_CUTOFF) { if (r > LJ_SWITCH_CUTOFF) {
real x = r-LJ_SWITCH_CUTOFF; real x = r-LJ_SWITCH_CUTOFF;
real switchValue = 1+x*x*x*(LJ_SWITCH_C3+x*(LJ_SWITCH_C4+x*LJ_SWITCH_C5)); real switchValue = 1+x*x*x*(LJ_SWITCH_C3+x*(LJ_SWITCH_C4+x*LJ_SWITCH_C5));
real switchDeriv = x*x*(3*LJ_SWITCH_C3+x*(4*LJ_SWITCH_C4+x*5*LJ_SWITCH_C5)); real switchDeriv = x*x*(3*LJ_SWITCH_C3+x*(4*LJ_SWITCH_C4+x*5*LJ_SWITCH_C5));
tempForce = tempForce*switchValue - ljEnergy*switchDeriv*r; tempForce = tempForce*switchValue - ljEnergy*switchDeriv*r;
ljEnergy *= switchValue; ljEnergy *= switchValue;
} }
#endif #endif
tempForce += prefactor*(erfcAlphaR+alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI); tempForce += prefactor*(erfcAlphaR+alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI);
tempEnergy += ljEnergy + prefactor*erfcAlphaR; tempEnergy += ljEnergy + prefactor*erfcAlphaR;
#else #else
tempForce = prefactor*(erfcAlphaR+alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI); tempForce = prefactor*(erfcAlphaR+alphaR*expAlphaRSqr*TWO_OVER_SQRT_PI);
tempEnergy += prefactor*erfcAlphaR; tempEnergy += prefactor*erfcAlphaR;
#endif #endif
}
dEdR += tempForce*invR*invR;
} }
dEdR += tempForce*invR*invR;
} }
#else #else
{ {
......
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