An isoline or a contour line of a function of two variables is a curve along which the function has a constant value. Isolines usually have a parallel trend.
Geometric art is a form of art based on the use and application of geometric figures. A geometric figure is any set or combination of points, lines, surfaces and solids. See also:
original image of problem
A mobile app or mobile application software is a computer program designed to run on smartphones and tablet computers.