This is documentation for Mathematica 3, which was
based on an earlier version of the Wolfram Language.
 SetAccuracy SetAccuracy[ expr , n ] yields a version of expr in which all numbers have been set to have an accuracy of n digits. When SetAccuracy is used to increase the accuracy of a number, the number is padded with zeros. The zeros are taken to be in base 2. In base 10, the additional digits are usually not zero. SetAccuracy returns an arbitrary-precision number even if the number of signficant digits obtained will be less than \$MachinePrecision. When expr contains machine-precision numbers, SetAccuracy[ expr , n ] can give results which differ from one computer system to another. SetAccuracy will first expose any hidden extra digits in the internal binary representation of a number, and only after these are exhausted add trailing zeros. 0.004``25 generates a number with all trailing digits zero and accuracy 25 on any computer system. SetAccuracy[ expr , n ] does not modify expr itself. See the Mathematica book: Section 3.1.5. See also: N, Accuracy, SetPrecision. Further Examples When an expression contains machine-precision real numbers, Mathematica tries to do all computations at machine-precision level. In[1]:= Out[1]= This causes a loss of accuracy. One of the inputs had an accuracy of 30 digits but the result has an accuracy of only 16 digits. In[2]:= Out[2]= In[3]:= Out[3]= By raising the accuracy of each subexpression, you can increase the accuracy of the overall result. In[4]:= Out[4]= In[5]:= Out[5]=