mathematical equation implmentation in c++

[wolle]

Thanks , but whatabout the first one ?

Well, if you have a time measure in nanoseconds and take the dB measure of that relative to 1 nanosecond you get exactly the same dB measure as if you instead have the measure in seconds relative to 1 second. In both cases you would use the same decibel formula,

ratio = 10 ^ (x/10)

to recover the ratio from the dB value. You just have to remember that the ratio in the nanosecond case has to be multiplied by 10^-9 to get the time in seconds.

The first of your formulas can be rewritten as

ratio = 10 ^ (8*x/10)

This is the ordinary dB formula but with a strange constant 8. I have no idea where it comes from. I first suspected it may have something to do with the 1 nanosecond reference but I have not been able to find out how. Maybe it's some application constant, perhaps a cubic volume with sides 2, I don't know. I suggest you ask your costumer for a clarification.