I have a set of values, power(W) versus frequency. First i transformed the Watt values to dBm, after i need to take the ifft for passing the time domain. More clearly, in 'freq' variable there is a frequency values from 0 Hz to 10000Hz. In 'data' variable, there is a power values corresponds to the frequency values. When I do ifft(data); , I dont use any frequency values, and It is meaningless. I know that for idft, the point number is important but how can I do this transform with the frequency values ?
Not sure if I understand your question correctly but just talking about IFFT operation itself, it has nothing to do with the frequency value. FFT and IFFT are just mathematical operations. The frequency value is what you use to interpret the data and gave them some physical meanings