Hi, please can I ask you, how would you decompose some field (eg. pressure field in a given space) into a fourier serie with a linear term? This is my problem: In my equations, the pressure acts in the form (the pressure was transformed only in the x axis, y axis stays in real space, the k is a wave vector for discrete fourier in x) p(k,y)=c1(k)+c2(k)*y +Sum[ i Cfourier exp(ik pi y) ] but of course the input into the program is a discrete field or a function, all in real space. I know there is a lot of libraries and scripts for FFT, but how to use it - I have the linear term here but I don't know the c1(k), c2(k)... Thank you for any tip!