Cadence Skill - Totally Buggy?

Hi,

1. Generally speaking, you NEVER EVER match floating numbers as you did. Use booleans, integers but not floating numbers. This is true in all the languages. Andrew has explained the reasons why. BTW, there was a little tiny typo in Andrew's. The sstatus command is: 

 sstatus(fullPrecision t)

i.e. with no tick '

2. What's wrong with your Skill ? What is the problem you want us to check for you ? You could have put some comments in your code for people to get some clues. Well, I have tried your Skill and don't see any errors, it ran well. Have you had any errors at all ? If yes please post the message.

Cheers,

Riad.

Thanks Berk....

apply('min Lst)  works....

but still there are issues....

Actually I wanted to search for all"metal-4 drawing" layers, find their width, map it to the closest value in a specific list ("mapwlist") and print the newly mapped width. I made mapw function for mapping.It should have mapped a rectangle of 0.142 micron width to 0.142, instead it maps it to 0.066! I did a tracef() and found all these anomalies. I am sure it's not the issue with floating point round off.

when I type mapw(0.142), it returns 0.142, but if I run the whole script, it maps 0.142 to 0.066.

 Please Help me if you know about this.

Thanks in Advance! :-) 

There are indeed rounding errors in the code (try putting:

  printf("Original Width= %.16f\n" width)

before the call to mapw(). However, that's not the real problem - it's the fact that your algorithm for finding mindiff is totally wrong! For a start, it's horrendously inefficient:

1. You traverse the list once to check for an exact match
2. You traverse the list again finding all the differences from w
3. You use a for loop to traverse the difference list, using nth() to access each index - which in turn traverses the list from scratch. You should never use nth() within a for loop - that's what foreach is for. Otherwise it's O(N^2) - which is inefficient.
4. You compare against nth(i-1 dlist) - so again traverse the list within the list - and find if the current difference is bigger than the previous difference - if it is, you set mindiff to be the previous difference. Can't see what purpose this is - it's going to give you the second to last difference in the list in this case (and since the list is reversed, this corresponds to the second entry in mapwlist, i.e. 0.066). A few printf's in the code show that it's getting things wrong.
5. Then you traverse the list again checking the differences against the found mindiff to find which matches.

So that's many traversals of the list (including list traversals within list traversals), and an incorrect algorithm. In addition, you should name your functions with a sensible prefix - there's a global name space, and Cadence uses functions with rather similar names - e.g. mapc, map, maplist, mapcar, mapcan - so there's a high risk of clashing with a Cadence function.

You also should define the function before it's used...

Anyway, here's a better (simpler and more efficient) implementation of "CADOmapw":

procedure(CADOmapw(w)
  let((mapwlist mindiff closestw)
    mapwlist='(0.052,0.066,0.072,0.09,0.1,0.142,0.23)
    ;--------------------------------------------------------------------
    ; Return value of the if is the closest w
    ;--------------------------------------------------------------------
    if(w>=0.7 then
      w
    else
      foreach(mpw mapwlist
	delta=abs(w-mpw)
	when(!mindiff || delta<mindiff
	  closestw=mpw
	  mindiff=delta
	) ; when
      ) ; foreach
      closestw
    ) ; if
  ) ; let
) ; procedure

Regards,

Andrew.