docs: public static double logpdf(double val, int v) {
      return GammaDistribution.logGamma((v + 1) * .5) - GammaDistribution.logGamma(v * .5) //
          - .5 * FastMath.log(v * Math.PI) + FastMath.log1p(val * val / v) * -.5 * (v + 1);
    }