Subchapters:

Working with arrays

There is a lot of operations on arrays, have a look to the manual. The last one presented here will be total.:

        IDL> proj1 = total(image1,1)
        IDL> proj2 = total(image1,2)
        IDL> grand_total = total(image1)

Here the proj1 and proj2 are vector resulting of the sum of the image1 on the x and y axis respectively. It can be seen as a projection along a direction. You can normalize it by:

IDL> proj1 = total(image1,1) / (size(image1))[1]
IDL> proj2 = total(image1,2) / (size(image1))[2]

The grand_total is the sum of all the elements of image1. The mean of the array is:

IDL> mean = total(image1) / n_elements(image1)

But can also be obtained by:

IDL> print,moment(image1)
0.500508 0.0832250 -0.00195926 -1.19825

The first element is the mean:

IDL> print,(moment(image1))[0]
0.500508