LiveCode Forums

Hi,

I'm using atan2 function to perform a calculation in Livecode.

Coud someone explain me why the result of : give me -0.114461 in livecode

and

=ATAN2(-7,56;65,76)

give me 1,685257 in excel

Thanks if you could help me

The result of the atan2 function is returned in radians. To get this result in degrees, use the following custom function:
function atan2InDegrees firstArg,secondArg
return atan2(firstArg,secondArg) * 180 / pi
end atan2InDegrees

see http://docs.runrev.com/Function/atan2

regards,

Paul

Hi.

The order of the arguments in atan2(x,y) is not unique, be very cautious with that!
This solves your problem:

Excel atan2(x, y) = LC atan2(y, x) -- interchange x and y

that is, with your example LC atan2(65.76, -7.56) = 1.685257 = Excel atan2(-7.56, 65.76).

This is from the built-in Dictionary:

The result of the atan2 function is returned in radians. To get this result in degrees, use the following custom function:

function atan2InDegrees firstArg,secondArg
return atan2(firstArg,secondArg) * 180 / pi
end atan2InDegrees

And, look at this: LibreOffice's "Excel rip-off" CALC uses the opposite order of variable to LiveCode just like Excel.

But, for those who REALLY CARE, while BBC BASIC does NOT implement atan2 one can do this:

10 DEF FNatan2(y,x) : ON ERROR LOCAL = SGN(y)*PI/2
20 IF x>0 THEN = ATN(y/x) ELSE IF y>0 THEN = ATN(y/x)+PI ELSE = ATN(y/x)-PI

which, you will notice, uses the same variable order as LiveCode.

Nice!
Interchanging values in the ATAN2 arguments work perfectly.

Thank you guys