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#include <alignment/statistics/cdfs.hpp>
float NormalCDF(float mu, float sigmaSq, float x)
{
float nStdDev = (x - mu) / sqrt(sigmaSq);
if ((int)nStdDev <= -10.0) return 0;
if ((int)nStdDev >= 10.0) return 1;
int cdfindex = 1000 + 100 * nStdDev;
assert(cdfindex >= 0);
assert(cdfindex <= 2000);
if (cdfindex == 2000) {
return 1;
}
// std::cout << "nstdev: " << nStdDev << " mu " << mu
// << " sigma " << sigmaSq << " x " << x
// << " norm cdf index: " << cdfindex << std::endl;
return NormCDFTable[cdfindex];
}
float PoissonCDF(float lambda, int a, int b)
{
float cdf = 0;
int i;
for (i = a; i <= b; i++) {
// std::cout << "poiss " << lambda << ", " << i
// << " " << Poisson(lambda, i) << std::endl;
cdf += Poisson(lambda, i);
}
return cdf;
}
float PoissonCDF(float lambda, int a)
{
float cdf = 0;
int i;
float p;
float epsilon = 0.000000000001;
if (lambda > (int)(FactorialTableLength * 2 / 3)) {
// lambda is too large, use normal approximation.
// std::cout << "using table: lambda: " << lambda
// << " a: " << a << std::endl;
return NormalCDF(lambda, lambda, a);
}
for (i = 0; i <= a; i++) {
p = Poisson(lambda, i);
if (p < epsilon and i > (int)lambda) break;
// std::cout << "p: " << p << std::endl;
cdf += p;
}
return cdf;
}
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