| A vector or a matrix.|
| A positive integer whose default value is assumed to be |
| A vector or matrix of numbers computed by differencing the input |
For a vector input,
diff(x) returns the array
[ x-x , x-x , x-x ....] .
x is a matrix, the finite differnces are calculated column by column.
diff(x,k) calculate the
k'th difference by differencing the input array
>>a=[4 10 12 15]'