Increasing or Decreasing Order between field values

Hi Folks.

  I want to find the positive or negative difference between consecutive values or increasing or decreasing order.

for eg:      field A     fieldB      fieldC      FieldD

               0             10          20           40               ----------------->   Increasing Order

               100          70         50           0                ------------------->   Decreasing Order

                0            30         0             50               -------------------> finding the blank value between values

how can i find the above increasing or decreasing order in ABAP.

Thanks,

Smriti