McIDAS-V Support Forums

Hi,

I was using the sub(a,b) formula through Formulas-->Simple Difference a-b

I had loaded the 2 most recent GOES East images

For Field: a, I selected Use Selected and then chose the Second most recent image.

This is not retained for Field: b



I tested the region selection, the region from field a is applied to the region for field b.


McV 1.6 2015-12-04 build

Joleen

Hi Joleen -

I've been testing this out for a bit, and it seems that even though the actual Times tab for the 'b' field in the Field Selector window doesn't update to match the 'a' field, it does actually pull out the correct time(s) to match the 'a' field. Is this what you are seeing, or are you actually getting incorrect results or an error if you don't manually set the Times tab for field 'b' to match field 'a'?

Thanks -
Bob

I had not actually tested to see if the times were mixed. I just selected the time I wanted. However, if for the first subtraction, I leave the field selector as is, (having both the first and second most recent times highlighted), and then on the y axis, specifically select the second most recent time for field b in the subtraction, I get a straight line. I believe that what you noted is correct. While the time is not highlighted correctly, the result is the time from field a persists to field b when field a and field b are from the same data source.

Joleen

Thanks for verifying that this still works correctly for you, even if you don't manually set the Times tab of field 'b' to match field 'a'.

I agree that this is confusing, especially since any domain set in the Region tab for field 'a' is reflected in field 'b'. I wrote up Inquiry 2236 to cover making the Times tab for field 'b' match field 'a' assuming you are working with one data source in the formula.

- Bob