Power Pivot Principles: The A to Z of DAX Functions – ATAN
21 September 2021
In our long-established Power Pivot Principles articles, we are starting a new series on the A to Z of Data Analysis eXpression (DAX) functions. This week it’s ATAN without colour …
The ATAN function
This function returns the principal value of the arctangent (inverse tangent) of a number (which is not the same as the reciprocal of the tangent). This needs some explanation. Consider a right-angled triangle:
Using the age-old mathematics mnemonic SOHCAHTOA, we get:
- sin x = opposite / longest side (hypotenuse) = O/H
- cos x = adjacent / hypotenuse = A/H
- tan x = opposite / adjacent = O/A
- arctan y = tan-1 y is the angle whose tangent is y.
This may be charted as follows:
The arctangent is the angle whose tangent is number. The returned angle is given in radians in the range (-pi/2) to (pi/2).
The syntax is very simple:
It has only one argument:
- number: the tangent of the angle you want.
Please see my example below:
If you want to convert the result from radians to degrees, simply multiply it by 180/PI () or use the DEGREES function.
The example is shown below:
Again, this is straightforward.
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