Write a program which will be able to display and rotate area described by function of two parameters z = f(x,y). The area should be displayed as a set of sections parallel with axis x and axis y (that means 3D form of graph).
After the start, program will ask you to type in a function.
Function is defined by an expression which can contain variables x and y,
numeric constants, parenthesis '(' and ')', operators '+' (add),
'' (subtract and unary minus), '*' (multiply), '/' (divide), '^'
(power to) and functions sqrt
(square root), sin
(sine),
cos
(cosine), tan
(tangent) a ln
(natural logarithm).
After that, program will ask you for interval of drawing for each of variables x and y. After displaying area determined by the function, it will be possible to rotate the graph around zaxis (by keys leftarrow and rightarrow) and around xaxis (by keys uparrow and downarrow).
The program will automatically determine optimal size of the graph.
Function: 4*cos(sqrt(2*x^2+y^2))/sqrt(x^2+y^2)

Interval for x and y: from 10 to 10 