Added DFT matrix
Change the name of function
Minor change
PEP8 Style
import xrange from sympy core
Fix #7206: Equality with matrices.

Equality was changed to support objects with an _eval_Eq method.  This allows
objects to define alternative algorithms for determining equality.  Such a
method was implemented in ImmutableMatrix.
Merge pull request #7278 from debugger22/dft_matrix

Added DFT matrix in physics matrices
Merge pull request #7281 from Tempel/7206_matrix_eq

Fix #7206: Equality with matrices.
Added taylor_term for sec(x)

Added taylor_term for sec(x).
Added unit tests corresponding to it.

Reference terms can be found here[1][2]

[1]https://www.efunda.com/math/taylor_series/trig.cfm
[2]https://en.wikipedia.org/wiki/Taylor_series

Updated variable usage, fixed formatting

Removed the declarations from the function call.
Added newline at the end.
Space after `,`

Added @cacheit. Fixed comments

Added @cacheit decorater.
Added space after `#` in comment.