343-Graph in two variables.sagews

x,y=var('x y')
u,v=var('u v')
html('<h2>Graph in two variables</h2>')
@interact
def _(func=input_box('2*x^3+x*y^2-5*x^2+y^2',label="f(x,y)=",type=str), xmin=-1,xmax=3, ymin=-1,ymax=3,\
 st_points=input_box('(0,0),(5/3,0)',label="points", type=str),\
 show_planes=("Show zero planes", False),  show_axes=("Show axes", True)):
 f=sage_eval('lambda x,y: ' + func)
 A=plot3d(f(x,y),(x,xmin,xmax),(y,ymin,ymax),opacity=0.5)
 html(r'Function $ f(x,y)=%s$ '%latex(f(x,y)))
 st_p=sage_eval('('+st_points+')')
 for current in range(len(st_p)):
   A=A+point3d((st_p[current][0],st_p[current][1],f(st_p[current][0],st_p[current][1])),size=9,rgbcolor='red')
 if show_planes:
   A=A+plot3d(0,(x,xmin,xmax),(y,ymin,ymax),opacity=0.3,rgbcolor='gray')
   zmax=A.bounding_box()[1][2]
   zmin=A.bounding_box()[0][2]
   A=A+parametric_plot3d((u,0,v),(u,xmin,xmax),(v,zmin,zmax),opacity=0.3,rgbcolor='gray')
   A=A+parametric_plot3d((0,u,v),(u,ymin,ymax),(v,zmin,zmax),opacity=0.3,rgbcolor='gray')
 if show_axes:
   zmax=A.bounding_box()[1][2]
   zmin=A.bounding_box()[0][2]
   A=A+line3d([(xmin,0,0), (xmax,0,0)], arrow_head=True,rgbcolor='black') 
   A=A+line3d([(0,ymin,0), (0,ymax,0)], arrow_head=True,rgbcolor='black') 
   A=A+line3d([(0,0,zmin), (0,0,zmax)], arrow_head=True,rgbcolor='black') 
 show(A)