More numbers in irrational numbers

Question

>>> str(1.41421356237309504880168872420969807856967187537694807317667973799073247846210703885038753432764157273501384623091229702) '1.41421356237' 

Is there a way to get str () to write more digits of a number into a string? I do not understand why it truncates by default.

Answer 1

Try the following:

 >>> from decimal import * >>> Decimal('1.41421356237309504880168872420969807856967187537694807317667973799073247846210703885038753432764157273501384623091229702') Decimal('1.41421356237309504880168872420969807856967187537694807317667973799073247846210703885038753432764157273501384623091229702') 

The float literal is truncated by default to fit in the space available to it (i.e. not because of str ):

 >>> 1.41421356237309504880168872420969807856967187537694807317667973799073247846210703885038753432764157273501384623091229702 1.4142135623730951 

If you need more decimals, use decimal .

Answer 2

Python floating point numbers only use double precision, which is 64 bits. They simply cannot represent (significantly) more numbers than you see.

If you need more, look at the built-in decimal or mpmath module .

Answer 3

The Python compiler trims; your floating literal has higher precision than can be represented in the double C. Express the number as a string in the first place if you need higher precision.

Answer 4

This is because it is converted to float. This is not a conversion to the string calling it. You must use decimal.Decimal to represent such numbers with high precision.