next up previous contents
Next: 2.3.16 Multiple Variable Access Up: 2.3.15 Sequential Access Previous: 2.3.15 Sequential Access

Example (Fortran application)

 

Assume a 2-dimensional array with sizes [2,3], column majority, a record variance of VARY, dimension variances of [VARY,VARY], nine (9) physical records written, and that the current sequential value has been set to record number 7 and indices [2,2]. Consecutive sequential reads would cause the following values to be read and returned to the application:

                     7(2,2) 7(1,3) 7(2,3)
8(1,1) 8(2,1) 8(1,2) 8(2,2) 8(1,3) 8(2,3)
9(1,1) 9(2,1) 9(1,2) 9(2,2) 9(1,3) 9(2,3)
END_OF_VAR
...where r(i,j) is a physically stored value with r being the record number, i the first dimension index, and j the second dimension index. ( r, i, and j are physical record numbers and dimension indices.) The next sequential read after the last physical value would cause a status code indicating the end of the variable to be returned ( END_OF_VAR).

Had the dimension variances been [NOVARY,VARY], the values read would have been

       7(1,2) 7(1,3)
8(1,1) 8(1,2) 8(1,3)
9(1,1) 9(1,2) 9(1,3)
END_OF_VAR
Note that specifying the virtual value 7(2,2) as the current sequential value caused physical value 7(1,2) to actually be selected (because the first dimension variance is NOVARY).

Sequential access for rVariables is performed using the <GET_,rVAR_SEQDATA_> and <PUT_,rVAR_SEQDATA_> operations of the Internal Interface. Sequential access for zVariables is performed using the <GET_,zVAR_SEQDATA_> and <PUT_,zVAR_SEQDATA_> operations.



cdfsupport@nssdca.gsfc.nasa.gov