ps command help

Hi,

I am trying to get a summary of the CPU,Memory utilised by every user in a system using the "ps" command.
I went through the man page and couldn't get the exact result.
The best i could manage was:

ps -e -o pcpu,pmem,user,args --sort user 

This doesn't add up the resource consumption by each user and summarise it.
BTW, I see a --cumulative argument,but i am not sure how to use it.

Any help is appreciated.

Note - I understand that we can use "prstat -a" and get the desired result. But my intention here is to explore and undertand the "ps" command.

Thanks
HG