﻿ Sample Problems > Usage > Implicit_Curves > implicit_curve_surface

# implicit_curve_surface

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# implicit_curve_surface   { 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