How to use Custom Function

[NathanAshton]

Hi Guys,

I need some help in getting a Custom Function to work. I am using one of Brian Dunnings Latitude & Longitude functions to calculate the distance between points. I copied and pasted it into a calculation field and it works great. I now want to use his "fnLatLon.bearing" function. It requires the use of his "Atan2" function.

How do I get these functions to work? I can prob put the fnLatLon.bearing function into a calculation field (I assume) but it doesn't work for atan2. If I put atan2 into a custom function (copy and paste) I get and error about "X" being an invalid field or something.

Cheers

[comment]

It's difficult to advise without seeing the actual functions and with such vague description of the error message. In general, if a custom function requires another custom function, you must define the pre-requisite function first. Only then you will be able to define the other one.

[Lee Smith]

Do you need to update your profile? You can only write Custom Functions if you have the Advance Edition of FileMaker?

Lee

[NathanAshton]

Sorry, I should be more specific. I'm currently using FM 10 Pro Advanced.

atan 2 function:

Let ( [

a =

If ( x > 0 ; Atan( y / x ) ;

If ( x < 0 ; Pi - Atan( -y / x ) ;

Pi / 2 * Sign ( y ) ) );

result = Mod( a; 2 * Pi)

];

result

)

If I copy this into a new custom function, I get the error "specified parameter cannot be found" and the first x is highlighted.

Edited March 28, 2009 by Guest

[Lee Smith]

I made a quick sample of the two Functions, notice that you need to do the CF for [color:blue]Atan2 before you do the CF [color:blue] fnLatLon.bearing

also, note that in the [color:blue]fnLatLon.bearing CF is calling [color:blue]fnAtan2 instead of [color:blue]Atan2, although it is the Atan2 CF you need, so just change the fnAtan2 to Atan2.

BTW, I did not get the answer shown in the example at Brian Dunning's site???

I'll leave that to you to figure out where I errored, or the Author did. :

HTH

Lee

atan2.fp7.zip

Edited March 28, 2009 by Guest

[Lee Smith]

BTW, FileMaker points to errors in calcultions, as you have described. In this case, the [color:red]x needs to be added as a parameters, along with [color:red]y in order for Atan.2 to be correct. Also, in fnLatLon.bearing, you will need to create the parameters of [color:red]lat1, lat2, lon1 and lon2 for it to work. Open my example file, and I think you will see what I mean.

HTH

Lee

[color:blue]To change your Profile, go to the menu bar above, MY PROFILE >> Control Panel >> FileMaker Questions.

Edited March 28, 2009 by Guest

[NathanAshton]

Thanks Lee, I now have the function working but like you the results aren't accurate. No probs though, I'm sure I can troubleshoot through that.

Actually, just sorted it out. Adding 90 degrees give the correct answer.

Cheers

Edited March 28, 2009 by Guest

[Lee Smith]

Don't forget to change your [color:red]Profile so that we will know how to respond to your questions in the future.

Lee