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## plot multiple 3d graf (cilinder / shpere)  1-Newbie

## plot multiple 3d graf (cilinder / shpere)

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.

1 ACCEPTED SOLUTION

Accepted Solutions  24-Ruby IV
(To:llourenço)

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.

5 REPLIES 5  24-Ruby IV
(To:llourenço)

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.  1-Newbie
(To:Werner_E)

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..  24-Ruby IV
(To:llourenço)

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.  1-Newbie
(To:Werner_E)

Many thanks for the explanation WE.

Regards.  23-Emerald II
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