implicit_curve_surface

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implicit_curve_surface

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{ IMPLICIT_CURVE_SURFACE.PDE

 

 This example shows how FlexPDE can be used to plot polynomial

 expressions and their derivatives. This can be helpful in many

 different scenarios, but is presented here because expression

 F3 is used in the example IMPLICIT_CURVE_BOUNDARY.PDE.

}

Title 'Example Surfaces'

Coordinates cartesian2

Select contours=50

 

Definitions

 f1 = (x^2+y^2)^3-4*x^2*y^2

 f2 = (x^2+y^2)^2-4*x*y

 f3 = (x^2+y^2)^2 - 3*x^2*y - y^3

 

Boundaries

region 1

  start(-2,-1)

  line to (2,-1) to(2,2) to (-2,2) to close

 

Plots

contour(F1)

contour(F1)     zoom(-1,0, 2,1)

contour(dx(F1)) zoom(-1,0, 2,1)

contour(dy(F1)) zoom(-1,0, 2,1)

elevation(dx(F1),dy(F1)) from (-1,0) to (1,0)

 

contour(F2)

contour(F2)     zoom(-1,0, 2,1)

contour(dx(F2)) zoom(-1,0, 2,1)

contour(dy(F2)) zoom(-1,0, 2,1)

elevation(dx(F2),dy(F2)) from (-1,0) to (1,0)

 

contour(F3)

contour(F3)     zoom(-1,0, 2,1)

contour(dx(F3)) zoom(-1,0, 2,1)

contour(dy(F3)) zoom(-1,0, 2,1)

elevation(dx(F3),dy(F3)) from (-1,0) to (1,0.0)

 

End