The shifted up one period of cosine function with field under it normalized to 1 is proposed to be use as the unconventional model of probability density function (PDF) of symbol +COS. It could approximate Normal probability distribution in the range ± 2,5 standard deviation with accuracy of about ±0,02, which is fully acceptable in the evaluation of measurement uncertainty. Properties of the cosine based PDF are considered. The possibility of its applications in the routine data assessment and in virtual instruments with automatic uncertainty calculations is discussed and recommended.
function of closeness of probability, approximation of normal distribution