Tangent plane in 3D - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- Thread: Tangent plane in 3D (/thread-12031.html) Tangent plane in 3D - Tonig00 - 12-27-2018 07:00 AM Hello I would like to draw a tangent plane to a function in 3D APP. I work in CAS mode in the following example: For example FZ1(X,Y)=X^1/3 * Y^1/3: I introduce this equation in "Symbolic View" in de 3D APP. It draws it correctly when I press "Plot". Then I introduce the plane equation in a point (for example (1,1)): FZ2(X,Y)=FZ1(1,1)+dFZ1(X,Y)/dX * (X-1) + dFZ1(X,Y)/dY * (Y-1) When I press Plot it does not draw the plane. I have tried to derivate it directly dFZ1(X,Y)/dX and it gave me 0, Could somebody give me an idea to how to trace that plane? Thanks very much Toni RE: Tangent plane in 3D - toshk - 12-27-2018 06:26 PM CAS; type FZ1(x,y) enter // gradient; numerical del operator nDeriv(x^(1/3)*y^(1/3),{x,y}) enter; //for Partial derivative do this instead nDeriv(x^(1/3)*y^(1/3),x) enter; nDeriv(Ans,y) enter; save your appropriate ans(del or Partial your choice) in say FZ2; change x,y to X,Y iferr do the steps... doing this FZ2:= nDeriv(x^(1/3)*y^(1/3),{x,y}) enter; might not work; applies to Function App too;