\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}\left(\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{\frac{1 - k}{2}}{2}\right)}\right) \cdot {\left({2}^{\left(\frac{1 - k}{2}\right)} \cdot {\left(n \cdot \pi\right)}^{\left(\frac{1 - k}{2}\right)}\right)}^{\frac{1}{2}}double f(double k, double n) {
double r62231 = 1.0;
double r62232 = k;
double r62233 = sqrt(r62232);
double r62234 = r62231 / r62233;
double r62235 = 2.0;
double r62236 = atan2(1.0, 0.0);
double r62237 = r62235 * r62236;
double r62238 = n;
double r62239 = r62237 * r62238;
double r62240 = r62231 - r62232;
double r62241 = r62240 / r62235;
double r62242 = pow(r62239, r62241);
double r62243 = r62234 * r62242;
return r62243;
}
double f(double k, double n) {
double r62244 = 1.0;
double r62245 = k;
double r62246 = sqrt(r62245);
double r62247 = r62244 / r62246;
double r62248 = 2.0;
double r62249 = atan2(1.0, 0.0);
double r62250 = r62248 * r62249;
double r62251 = n;
double r62252 = r62250 * r62251;
double r62253 = r62244 - r62245;
double r62254 = r62253 / r62248;
double r62255 = 2.0;
double r62256 = r62254 / r62255;
double r62257 = pow(r62252, r62256);
double r62258 = r62247 * r62257;
double r62259 = pow(r62248, r62254);
double r62260 = r62251 * r62249;
double r62261 = pow(r62260, r62254);
double r62262 = r62259 * r62261;
double r62263 = 0.5;
double r62264 = pow(r62262, r62263);
double r62265 = r62258 * r62264;
return r62265;
}



Bits error versus k



Bits error versus n
Results
Initial program 0.4
rmApplied sqr-pow0.5
Applied associate-*r*0.5
rmApplied div-inv0.5
Applied pow-unpow0.5
Simplified0.5
rmApplied unpow-prod-down0.4
Final simplification0.4
herbie shell --seed 2019323
(FPCore (k n)
:name "Migdal et al, Equation (51)"
:precision binary64
(* (/ 1 (sqrt k)) (pow (* (* 2 PI) n) (/ (- 1 k) 2))))