Solved: Re: plot multiple 3d graf (cilinder / shpere)

llourenço · ‎Oct 22, 2014

Hello there, how are you?

I have a problem with math graphics.

the equation of a cilinder is cilinder(roh, teta) and the shpere, like this: and th final plot, with wrong equation.

I need to draw a sphere with a equation of a cilinder, so I try to z:=-1.5,-1.6..-4.5 instead of Z:=-1.5

But funcion CreateMesh gives error becouse Z is a array of numbers instead a number?

By the way, anyone know hot to plot a three variable 3d? like Sph(x, y, z) := ...??

regards.

Werner_E · ‎Oct 22, 2014

Mathcad's 3D plot can't handle solids. All you get by Createmesh is a mesh on a surface. The same is true for the sphere, too- you just can't tell as long as you draw complete speheres.

In case of the cylinder you may cheat and add top and bottom circular disk - this is what your function Cil is perfect for 😉

Anyway my documentation tells me that input variables are roh and theta..

Look at the drawing you provided. Cylinder coordinates are a way to address a point in 3D space, so we need three of them - rho, theta and z.

If z is constant (as in your function) we get a horizontal plan; if we limit r we get a circulat disk in that plane; if we limit theta, we get a sector.

If rho is constant, we get a cylinder with the applicate (z-axis) as cylinder axis. If we limit z we get what most people would image when they are talking about a cylinder surface (most people don't accept that a mathimatical cylinder is endless and has no specific height).

If theta is constant, we get a plane which includes the applicate.

View solution in original post

Werner_E · ‎Oct 22, 2014

In case of the cylinder your equation is wrong! The radius rho is constant, similar to the radius r in case of the sphere. Any point on the surface of the cylinder depends on theta and z, so these two should be arguments of your function Cil.

For future questions please bear in mind that your chances of getting a satisfactory reply increase when you attach your worksheet.

llourenço · ‎Oct 22, 2014

Hello WE.

If I use theta and z, i will plot only surface of cilinder, and i wnat to plot inside also, like a filed cilinder.

Using thet and z only will draw outside, right?

Anyway my documentation tells me that input variables are roh and theta..

Werner_E · ‎Oct 22, 2014

Mathcad's 3D plot can't handle solids. All you get by Createmesh is a mesh on a surface. The same is true for the sphere, too- you just can't tell as long as you draw complete speheres.

In case of the cylinder you may cheat and add top and bottom circular disk - this is what your function Cil is perfect for 😉

Anyway my documentation tells me that input variables are roh and theta..

Look at the drawing you provided. Cylinder coordinates are a way to address a point in 3D space, so we need three of them - rho, theta and z.

If z is constant (as in your function) we get a horizontal plan; if we limit r we get a circulat disk in that plane; if we limit theta, we get a sector.

If rho is constant, we get a cylinder with the applicate (z-axis) as cylinder axis. If we limit z we get what most people would image when they are talking about a cylinder surface (most people don't accept that a mathimatical cylinder is endless and has no specific height).

If theta is constant, we get a plane which includes the applicate.

llourenço · ‎Oct 22, 2014

Many thanks for the explanation WE.

Regards.

StuartBruff · ‎Oct 22, 2014