Abstract: A method and a digital computer for providing the result of a calculation performed upon data having a floating point representation, with the number of exact significant figures in this result. With every mantissa of initial data is associated an item of error information having a floating point representation and which has a value of zero when the real value of the initial data and the value thereof in its digital representation coincide and which does not have a value of zero when the real value of the initial data and the value thereof in its digital representation do not coincide. The first operation is carried out by employing the digital representation and the item of error information of the mantissa in order to calculate a mean value of the mantissa of the result and the item of error information associated with the mean value.

Abstract: With every numerical data there is associated an item of truncation information (TA1, TB1, . . . ) which is true or false according to whether its value is or is not truncated in the representation employed, the calculation is carried out a number of times while disturbing the development of at least one procedure independently of the others, the disturbance consisting during the course of each elementary operation of adding on occasion and at random a bit of the lowest significance to the mantissa of each number the associated item of truncation information of which is positive, and the mean value and the standard deviation of the different results provided are worked out in order to determine the number of exact significant figures in one of these results.