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XMM-Newton Science Analysis System


ssclib (ssclib-3.24) [xmmsas_20050815_1803-6.5.0]

Meta Index / Home Page / Poissonian statistics and source

Integrated Gaussian probability

This function returns the probability that a gaussian-distributed variable $y$ will depart from the mean $y_{\rm {mean}}$ by greater than $abs(y-y_{\rm {mean}})$. For values obeying a gaussian distribution of standard deviation $\sigma$, the probability $P$ of a given $y$ value (or greater) occurring by chance is

$$P(y) = 1 - erf \big[ abs(y - y_{\rm {mean}})/\sigma\sqrt{2} \big].$$

  function integratedGaussProb(testY, meanY, sigma) result(probability)
    real(single), intent(in) :: testY, meanY, sigma
    real(single) :: probability
  end function integratedGaussProb