Trying to find a source segment of a formula

[Marvo]

I'm trying to dissect the following formula to better understand. Where can I find the information for s and t please? Its not in name manager.

=LET(t,ALL!$K:$K,s,SEQUENCE(ROWS(t)),MAX(FREQUENCY(IF(t="W",s),IF(t<>"W",s))))

Thanks.

[Glenn Kennedy]

=LET(t,ALL!$K:$K,s,SEQUENCE(ROWS(t)),MAX(FREQUENCY(IF(t="W",s),IF(t<>"W",s))))

T is defined by the bit in red and s by the bit in blue.

[Marvo]

So the idea is once you've written it once, you don't have to write it again?

[Glenn Kennedy]

If you think of =LET() as being a bucket, it's easier to understand. It doesn't of itself, actually do ANYTHING.

LET will keep various sub-formulae for convenient (multiple) re-use in the main formula. In your case, there are to subformulae, t & s. Instead of calculating them every time (which then gets slow) they are calculated once and each of them is used twice in the final formula. =LET() enable more complex functions to be calculated with greater efficiency.

[Marvo]

Thank you Glenn, I think I understand.

[Glenn Kennedy]

Finally, in these longer and longer formulae, I tend to put all the bits of the raw data that I need IMMEDIATELY after LET... to make it easier to adjust ranges, if needed. They're all there (and only there) at the start of the formula.

[AliGW]

In my words, the start of a LET clause sets various parameters that you go on to use in a formula.

So, for example, consider this:

=IF(COUNTIF(A:A,"Marvo")>1,"Happy Days",COUNTIF(A:A,"Marvo"))

which could be condensed to:

=LET(c,COUNTIF(A:A,"Marvo"),hd,"Happy Days",IF(c>1,hd,c))

You can give your parameters (almost) any name you like.

[Marvo]

Thank you Ali. I get it now.