Rosetta Code

Averages/Arithmetic mean: Difference between revisions

Page Discussion

Averages/Arithmetic mean (view source)

Revision as of 01:49, 9 May 2008

No change in size ,  16 years ago
m
→‎{{header|Fortran}}
Line 129:
=={{header|Fortran}}==
In ISO Fortran 90 or later, use the SUM intrinsic, the SIZE intrinsic and the MAX intrinsic (to avoid divide by zero):
REALreal, TARGETtarget, DIMENSIONdimension(100) :: Aa = (/ (i, i=1, 100) /)
REALreal, DIMENSIONdimension(5,20) :: Bb = RESHAPEreshape( Aa, (/ 5,20 /) )
REALreal, POINTERpointer, DIMENSIONdimension(:) :: Pp => Aa(2:1) ! pointer to zero-length array
REALreal :: MEANmean, ZMEANzmean, BMEANbmean
REALreal, DIMENSIONdimension(20) :: COLMEANScolmeans
REALreal, DIMENSIONdimension(5) :: ROWMEANSrowmeans
MEANmean = SUMsum(Aa)/SIZEsize(Aa) ! SUM of A's elements divided by SIZE of A
MEANmean = SUMsum(Aa)/MAXmax(SIZEsize(Aa),1) ! Same result, but safer code
! MAX of SIZE and 1 prevents divide by zero if SIZE == 0 (zero-length array)
ZMEANzmean = SUMsum(Pp)/MAXmax(SIZEsize(Pp),1) ! Here the safety check pays off. Since P is a zero-length array,
! expression becomes "0 / MAX( 0, 1 ) -> 0 / 1 -> 0", rather than "0 / 0 -> NaN"
BMEANbmean = SUMsum(Bb)/MAXmax(SIZEsize(Bb),1) ! multidimensional SUM over multidimensional SIZE
ROWMEANSrowmeans = SUMsum(Bb,1)/MAXmax(SIZEsize(Bb,2),1) ! SUM elements in each row (dimension 1)
! dividing by the length of the row, which is the number of columns (SIZE of dimension 2)
COLMEANScolmeans = SUMsum(Bb,2)/MAXmax(SIZEsize(Bb,1),1) ! SUM elements in each column (dimension 2)
! dividing by the length of the column, which is the number of rows (SIZE of dimension 1)
 
Anonymous user
Retrieved from "https://rosettacode.org/wiki/Special:MobileDiff/50019"