[ferret_users] Embedded expressions and @LOC

["Stephen R. Guimond" <guimond@xxxxxxxxxxxxx>]

Hello,
 I want to find the maximum value for each time step in an array of 
data, and then find the coordinate position that the maximum value 
occurs at.  I have used a loop in a script like this:

repeat/range=1:18:1/name=g (let max_val = lf[l=`g`,j=@MAX];let max_rad 
= lf[l=`g`,j=@LOC:`max_val`];say `max_val`;say `max_rad`;list/l=`g` lf)

However, "max_val" is not finding the precise locations of my maximum 
value.  I thought this had to do with precision, so I used 
`max_val,p=-3` in the @LOC statement to specify 3 decimal places, but 
there is still a problem.  See the output below.  For output 1, the 
@LOC value should be 150, but it comes up as 149.97.  For output 2, the 
@LOC value should be 50, but it comes up "bad" even though it has the 
exact same number.  Any ideas??

Thanks,
Steve

OUTPUT.....

result of `max_val,p=-3` = 5.309
result of @LOC = 149.97
            VARIABLE : LF
            FILENAME : quad_rain_trop.dat
            SUBSET   : 20 points (Y)
            TIME     : 01-AUG-2004 18:00
50     /  1:  3.298
100    /  2:  4.598
150    /  3:  5.309
200    /  4:  3.017
250    /  5:  1.740
300    /  6:  1.111
350    /  7:  0.669
400    /  8:  1.114
450    /  9:  0.663
500    / 10:  0.781
550    / 11:  0.900
600    / 12:  1.161
650    / 13:  1.535
700    / 14:  1.620
750    / 15:  1.194
800    / 16:  1.335
850    / 17:  0.660
900    / 18:  0.266
950    / 19:  0.682
1000   / 20:  0.547

result of `max_val,p=-3` = 5.331
result of @LOC = bad
            VARIABLE : LF
            FILENAME : quad_rain_trop.dat
            SUBSET   : 20 points (Y)
            TIME     : 02-AUG-2004 18:00
50     /  1:  5.331
100    /  2:  2.335
150    /  3:  2.186
200    /  4:  0.892
250    /  5:  0.329
300    /  6:  0.778
350    /  7:  1.785
400    /  8:  1.896
450    /  9:  1.289
500    / 10:  0.792
550    / 11:  1.213
600    / 12:  1.934
650    / 13:  1.697
700    / 14:  0.743
750    / 15:  0.828
800    / 16:  0.818
850    / 17:  0.999
900    / 18:  1.374
950    / 19:  1.599
1000   / 20:  2.458


=======================================================
Stephen R. Guimond
Graduate Research Assistant
Center for Ocean-Atmospheric Prediction Studies (COAPS)
Tallahassee, FL 32304
=======================================================

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