contentswe can go to straight to the python library referencebut there are also other options the command pydoc in the terminal window can be used to list information about module (trye pydoc math)or we can import the module in python program and list its contents with the built-in function dir import math print(dir(math)['__doc__''__file__''__loader__''__name__' pitfalls when programming mathematics usuallythe mathematical operations described above work as expected when the results are not as expectedthe cause is usually trivial error introduced during typingtypically assigning the wrong value to variable or mismatching the number of parentheses howeversome potential error sources are less obvious and are worth knowing abouteven if they are relatively rare round-off errors give inexact results computers have inexact arithmetic because of rounding errors this is usually not problem in computationsbut in some cases it can cause unexpected results let usfor instancecompute / and / * * print( "{ { }"the output with decimal places becomes most real numbers are represented inexactly on computertypically with an accuracy of digits neither / nor / are represented exactlyand the error is approximately - errors of this order usually do not matterbut there are two particular cases in which they can be significant in one caseerrors can accumulate through numerous computationsending up as significant error in the final result in the other casewhich is more likely to be encountered in the examples of this bookthe comparison of two decimal numbers can be unpredictable the two numbers and above are both supposed to be equal to onebut look at the result of this codeprint( = print( =