Hi, ALL

We suppose that x[n] and y[k] are a DFT pairs, i.e.

y[k]=1/N*sum_n(x[n]*exp(-2*pi*j*k*n/N)) n=0,1,...,N-1

where sum_n means the sum for n=0,1,N-1(similar for sum_k),

and dt is the sampling interval, df is the sampling frequency,

N is the sampling number.

To obey Parseval's theorem, we get

sum_n(x[n]*x[n])*dt=sum_k(y[k]*y[k])*df

since sum_n(x[n]*x[n])=N*sum_k(y[k]*y[k])

and df=1/(N*dt), also consider the amplitude symmetry of the real series,

we should multiply a coefficent to y[k]:

sqrt(2)*N*dt

but in SAC software, this value is N*dt/2,

so do you have any idea?

Thanks.