Precision
 Usage
Notes
 Further Examples
Here is an approximate real number.
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This gives the precision of the real number.
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This evaluates  attempting to get a result with precision  .
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The result has precision  .
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Mathematica treats  as a machine-precision number.
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This evaluates  using machine-precision numbers.
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This evaluates  using 30-digit precision numbers.
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In this case, the result has a precision slightly less than  .
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This evaluates  trying to get a result with precision  .
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Now the result has precision 30.
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If you give input as a machine number, N cannot give you high-precision output.
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SetPrecision can be used to convert machine numbers to high-precision.
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If you want an exact representation of  , then you have to convert it explicitly.
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