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[IDV #WUY-852966]: Defining a formula

> Yuan, Julian, or Sean,
> 
> Following up on my plaintive cry for guidance about creating a formula (to 
> calculate the magnitude of the gradient of a scalar): I managed to fake my 
> way to creating a working formula, but there are some loose ends.
> 
> In the Formula Editor dialog window, I specified the formula "mag(grad(S))".
> 
> I'm not sure what purpose the "Name" serves--I called it "Gradient_Magnitude".
> 
> I see that the "Description" is what shows up in Field Selector > Fields 
> column.
> 
> I was editing the "Horizontal Advection" formula to create my formula, and I 
> left everything else the same. That made sense for the group ("Grids"), and 
> maybe for displays ("Use all"). I don't have much sense of what the items 
> under the "Derived" tab are about, though. Leaving the parameter groups and 
> corresponding categories the same as for horizontal advection doesn't make 
> sense (the parameter groups are all about wind velocity components), but I 
> don't know what else to put there, if anything.
> 
Dave,
    It sounds to me that your formula is applied to any scalar and there is no 
dependent on any other specific parameter groups, so, you don't need to do 
anything on the Derived tab. The horizontal advection depends on the velocity 
fields, this is why those parameter groups being used here.

> If I want to propagate my formula to lots of student lab computers, it looks 
> like I just have to copy ~/.unidata/idv/DefaultIdv/derived.xml on my machine 
> to the same relative location on those machines. Is that right?
> 

There are several ways you can used to do this. The dervied.xml and local 
formula can be packed into a plugin and distributed to your students. It can 
also be distributed through a bundle. But only distribute the derived.xml is 
not enough.

Yuan
> -- Dave
> 
> ************************************************************
> *   Dr. Dave Dempsey                        |       ^   ___       \|/     *
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Ticket Details
===================
Ticket ID: WUY-852966
Department: Support IDV
Priority: Normal
Status: Closed