Volume of revolution

Assuming that you want to revolve this around the Y-axis I'd create a parametric surface in Gizmo. Here is an example. Suppose your function has the form:

Function fr(inr,rmax)

    Variable inr,rmax

    Variable x2=inr/rmax

    return sqrt(1-x2*x2)

End

I'd create a parametric surface of the desired resolution, e.g.,

•make/n=(101,101,3) ddd

•ddd[][][0]=p-50

•ddd[][][1]=q-50

•ddd[][][2]=fr(sqrt((p-50)^2+(q-50)^2),50)

Now create a new Gizmo and append a parametric surface. You can do so manually or simply execute the following recreation macro:

Window Gizmo0() : GizmoPlot

    PauseUpdate; Silent 1   // Building Gizmo 6 window...

    NewGizmo/N=Gizmo0/T="Gizmo0" /W=(536,44,1167,675)

    ModifyGizmo startRecMacro

    AppendToGizmo Surface=root:ddd,name=surface0

    ModifyGizmo ModifyObject=surface0 property={ srcMode,4}

    ModifyGizmo ModifyObject=surface0 property={ surfaceCTab,Rainbow}

    ModifyGizmo setDisplayList=0, object=surface0

    ModifyGizmo SETQUATERNION={0.571268,0.028073,0.091655,0.815146}

    ModifyGizmo autoscaling=1

    ModifyGizmo currentGroupObject=""

    ModifyGizmo compile

    ModifyGizmo endRecMacro

End

I hope this helps,

A.G.
WaveMetrics, Inc.

August 15, 2013 at 09:47 am - Permalink

s.r.chinn

With all due respect to the Gizmo-meister, A.G., my preference (with more tutorial transparency) for the parametric Gizmo surface would be expressed in terms of the rotation angle as one parameter, and the function argument axis as the other, as in:

function foo( rin, rmax)

    variable rin, rmax

    variable rho = rin/rmax

    return (cos(2*pi*rho))^2

end

function show()

    variable rmax =10

    make/O/N=(90, 100, 3) wsurf

    setscale/I x, 0, 2*pi,"" wsurf

    setscale y, 0, rmax, "" wsurf

    wsurf[][][0] = cos(x)* y

    wsurf[][][1] = sin(x) * y

    wsurf[][][2] = foo(y, rmax) // use this as

// a parametric surface for Gizmo

end

August 15, 2013 at 11:35 am - Permalink