||'''Book'''|| Advanced Engineering Mathematics ||
 ||'''Author'''|| Erwin Kreyszig ||
 ||'''Edition'''|| 8th Edition ||

/* code_begins */

{{{
x = var('x')
y = var('y')

T = x^2 - y^2
contour_plot(T, (x, -500, 500), (y, -500,500))}}}

/* code_ends */

 * '''Solution by''': 
  * ganesh, developer, space
  * bhanukiran, student, technical university of Delft
  * saransh, student, sobhit university