What kind of variable is the "detected amplitude" output of the Extract Single Tone Information Vi?

[PaulLara93]

I asked this question because I create an indicator for that output and it creates what looks like an array of a single element. 

Contrary to that if I use the VI "Tone Measurements" I get just a double.

Why is that? 

[RavensFan]

Attach your VI !!!!  Then we can see how you have it configured.

That subVI is polymorphic.  If the instance handles one channel, then it outputs a scalar.  If the instance handles N channels, then it outputs an array, each element is a value calculated for each waveform.  If you only put in one waveform (a 1-D array of waveforms with only one element), you'll get a 1-D array of amplitudes with only one element.