XSL - Get SUM of price

Question

I have a xml structure like:

 1481 test1 test2 

        

Answer 1

This transformation doesn't require the use of any extension functions and doesn't produce an intermediary tree -- in fact it runs with 0 additional memory and is suitable for streaming, if the XSLT processor recognizes tail-recursion:

When it is applied on the provided XML document:

  
    1481
    test1
    test2
    +798.27
  
  
    0741
    test2
    test2
    +399.14
  

The wanted, correct result is produced:

1187.4099999999998