How to create a matrix that contains members with specific different between each element ?

if I have matrix A that contains a distance between element n and n+1 :

A = [4 7 15]

How can I construct Matrix B that shows a result as

B = [1 5 12 27]

Answer 1

[per isakson]

Starter:

>> cumsum([1,A])
ans =
     1     5    12    27

[Pradya Panyainkaew]

Thank you so much sir.