For January and February: 



FACTOR = 365 (YYYY) + DD + 31 (MM - 1) + INT(YYYY - 1)/4) 



- INT(3/4[INT] ((YYYY - 1)/100) + 1] ) 



For March through December: 



FACTOR = 365 (YYYY) + DD + 31(MM - 1) - INT(4MM + 23) 



+ INT (YYYY/4) - INT(3/4[INT (YYYY/100) + 1]) 



In these formulas INT indicates using only the integer portion of the expression. 



The number of days between two dates is found by calculating the FACTOR for each 

 date, then finding the difference between the FACTORS. 



Vin. File Description: 



a. Input File 



Input to XTRACT is a NOAA tape of STD data. Specific information as to 

 tape characteristics will be on the tape itself. The following characteristics are assumed: 



TRACKS 



9 



DENSITY 



1600 Bits/Inch 



LOGICAL RECORD LENGTH 



80 Bytes 



BLOCKSIZE 



3200 Bytes 



RECORD FORMAT 



FB 



UNLABELED 





b. Output File 





Output from XTRACT is a disk file in packed decimal form. It is to read 

 into the IBM SORT utility. The following characteristics are used: 



LOGICAL RECORD LENGTH 18 Bytes 



BLOCKSIZE 6372 Bytes 



c. Structures Used 



The structures used for input and output of data in the EXTRACT program 

 are shown in Tables Al and A2. 



A2 



