Michael, I've being trying to use the idea of making a js file of the _FxGraph3D parameters but I'm having limited success.
Some work and some don't.

The following two work OK
Brian's leafsinh.js
moi.command.execCommand( 'FxGraph3D u;v;((exp(u) - exp((-1)*u))/2 + (exp(v) - exp((-1)*v))/2);-3.14159;3.14159;-3.14159;3.14159;15;15;0;0;0;UV' );
My MoebiusStripSolid.js
moi.command.execCommand( 'FxGraph3D cos(v)+u*cos(v/2)*cos(v);sin(v)+u*cos(v/2)*sin(v);u*sin(v/2);-0.4;0.4;0;6.20;15;15;1;1;1;UV' );

but this one (My TrumpetSolid.js) doesn't:
moi.command.execCommand( 'FxGraph3D cos(u)*sin(v);sin(u)*sin(v);cos(v)+log(tan(1/2*v));0;6.283;0.03;1.5;50;50;1;1;1;UV' );

For the life of me I can't see why.
When I try to run if from Max's Ext Scripts feature I get the following error: