Some functions can have many parameters, and among them, some might only be of interest in nonstandard situations. It would be practical if arguments could automatically be set to standard (default) values.
We demonstrate the use of default arguments by looking at the command norm in the module scipy.linalg. It computes various norms of matrices and vectors. More on matrix norms can be found in [10 ,§2.3].
The following calls for computing the Frobenius norm of the 
identity matrix are equivalent:
import scipy.linalg as sl sl.norm(identity(3)) sl.norm(identity(3), ord = 'fro') sl.norm(identity(3), 'fro')
Note that in the first call, no information about the keyword ord is given. How does Python know that it should compute the Frobenius norm and not another norm, for example, the Euclidean 2-norm?
The answer to the previous question is the use of default values. A default value is a value already given by the function definition. If...
