1. An information processing apparatus comprising: a receiving device for receiving a distribution data series including an extreme value of a value corresponding to a position on a coordinate axis and data describing a condition under which the distribution data series has been obtained; a first adjusting device for adjusting a first function parameter set to reduce an error between data generated by a first function and the distribution data series, the first function including the first function parameter set, the first function parameter set specifying the position of the extreme value, the ratio of a value at a first distance on the coordinate axis from the position of the extreme value in a first direction to the extreme value, and an order of expression of an exponent part of a function curve including an exponential form in the interval from the position of the extreme value to the first distance in the first direction; a second adjusting device for adjusting a second function parameter set to reduce an error between data generated by a second function and the distribution data series, the second function including the second function parameter set, the second function parameter set specifying the position of the extreme value, the ratio of a value at a second distance on the coordinate axis from the position of the extreme value in a second direction to the extreme value, and an order of expression of an exponent part of a function curve including an exponential form in the interval from the position of the extreme value to the second distance in the second direction; a calculator for calculating a characteristic coefficient identifying a Pearson function from a moment of a function including the first and second functions joined at the position of the extreme value; a storage device for storing the characteristic coefficient in a database in association with the data describing the condition under which the distribution data series has been obtained; an interpolator for interpolating a characteristic coefficient for condition data of interest from the characteristic coefficient stored in the database; and a distribution data calculator for calculating distribution data by a Pearson function identified by the interpolated characteristic coefficient.