How do I input a floor/ceiling to find an index?

[kebrown]

Hi all,

I'm still fairly new to Labview, so please bear with me if this has a very simple answer. I have an xy graph; the x is 'time' and the y is 'phase'. I want to determine what my phase is at a given time. I would just use the Index Array, but the 'time' array is not in integer values (i.e. index "10" might be something like 9.2 ps). What I would like to do is use Search 1D Array for the indices with a 10 ps floor/ceiling, and then interpolate the phase value for 10 ps. However, I cannot figure out how to do a floor/ceiling. In the mean time I'm working around it, but I would really like to be able to do this.

Thank you!

[candidus]

Take a look at the Interpolate 1D Array function. It takes a fractional index as input and does linear interpolation. You find it in the Array palette.

[MrHappyAsthma]

If you are just looking for a simple floor or ceiling operation, you can use the following: Round To +Inifinity and Round To -Infinity.

They can be found in the numeric palette:

[crossrulz · Accepted solution]

Use the Interpolate 1D Array and Threashold 1D Array.  This is assuming your X is sorted in an ascending order.

[BTC_Admin]

Look at "Threshold 1D Array", it pretty much does all that you're trying to do.

-DP

[kebrown]

Thank you so much, this is exactly what I needed!