Super Metrics for the cpu and memory average

Hello Guys,

I need the super metric for the

CPU Usage for a vm and Memory Usage for a VM.

There is already a metric present in the vrops for the CPU Avg of a VM = avg(${this, metric=cpu|usage_average})

The problem is need this metric showing for 30 days. i am looking for a metric which says 30 days, 60 days etc...

The basic formula is ((CPU Usage Today - yesterday - daybefore yesterday ..... 29 days)/30 days)

Can we do a custom metric for calendar or time  without using API?

Let me know any questions

Thanks