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Modified to improve part of stability, gradient checks still passing.

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This commit is contained in:
Neil Lawrence 2013-11-27 11:21:08 +00:00
parent 6da3fc5a89
commit 557d296d4c
1 changed files with 2 additions and 2 deletions
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4
GPy/kern/parts/sympy_helpers.cpp
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@ -179,7 +179,7 @@ double dh_dt(double t, double tprime, double d_i, double d_j, double l){
arg_2 = half_l_di - t/l;
double ln_part_2 = ln_diff_erf(half_l_di, arg_2);
return (d_i*(erf(d_i*l/2) - erf(d_i*l/2 - t/l))*exp(-d_i*t - d_j*tprime) - d_i*(erf(d_i*l/2 + tprime/l) - erf(d_i*l/2 - (t - tprime)/l))*exp(-d_i*(t - tprime)) + 2*exp(-d_i*(t - tprime) - pow(d_i*l/2 - (t - tprime)/l, 2))/(sqrt(M_PI)*l) - 2*exp(-d_i*t - d_j*tprime - pow(d_i*l/2 - t/l,2))/(sqrt(M_PI)*l))*exp(d_i*l/2*d_i*l/2)/(d_i + d_j);
return (d_i*exp(ln_part_2-d_i*t - d_j*tprime) - d_i*(erf(half_l_di + tprime/l) - erf(half_l_di - diff_t/l))*exp(-d_i*diff_t) + 2*exp(-d_i*diff_t - pow(half_l_di - diff_t/l, 2))/(sqrt(M_PI)*l) - 2*exp(-d_i*t - d_j*tprime - pow(half_l_di - t/l,2))/(sqrt(M_PI)*l))*exp(half_l_di*half_l_di)/(d_i + d_j);
}
double dh_dtprime(double t, double tprime, double d_i, double d_j, double l){
@ -190,5 +190,5 @@ double dh_dtprime(double t, double tprime, double d_i, double d_j, double l){
double arg_2 = half_l_di - diff_t/l;
double ln_part_1 = ln_diff_erf(arg_1, arg_2);
return (d_i*(erf(d_i*l/2 + tprime/l) - erf(d_i*l/2 - (t - tprime)/l))*exp(-d_i*(t - tprime)) + d_j*(erf(d_i*l/2) - erf(d_i*l/2 - t/l))*exp(-d_i*t - d_j*tprime) + (-2*exp(-pow(d_i*l/2 - (t - tprime)/l,2)) + 2*exp(-pow(d_i*l/2 + tprime/l,2)))*exp(-d_i*(t - tprime))/(sqrt(M_PI)*l))*exp(d_i*l/2*d_i*l/2)/(d_i + d_j);
return (d_i*(erf(half_l_di + tprime/l) - erf(half_l_di - diff_t/l))*exp(-d_i*diff_t) + d_j*(erf(half_l_di) - erf(half_l_di - t/l))*exp(-d_i*t - d_j*tprime) + (-2*exp(-pow(half_l_di - diff_t/l,2)) + 2*exp(-pow(half_l_di + tprime/l,2)))*exp(-d_i*diff_t)/(sqrt(M_PI)*l))*exp(half_l_di*half_l_di)/(d_i + d_j);
}