d <- scan("inp_FFT_1.csv",skip=3)
nn <- length(d)
z <- fft(d)
z1 <- Re(z)/nn
z2 <- Im(z)/nn
cc <- sqrt(z1*z1+z2*z2)
zz <- complex(re=z1*nn,im=z2*nn)
y <- Re(fft(zz,inverse=TRUE))/nn
out<- cbind(d,z1,z2,cc,y)
write.table(out,"out_FFT_1.txt",quote=F,append=F,row.names=F)
d z1 z2 cc y
5 0 0 0 5
32 3.87961256380478 2.07134405386938 4.3979381344821 32
38 2.74448051533946 -4.19010191002141 5.00890480199445 38
-33 2.47896579998472 -5.9762205702964 6.46996783163006 -33
-19 -3.375 -4.375 5.52550902632509 -19
-10 -2.09400457708259 1.92803176917456 2.84642963584018 -10
1 -3.61948051533946 1.18489808997859 3.80849349278122 0.999999999999996
-8 1.98542621329309 2.47559639334034 3.17340428422712 -8
-20 1 0 1 -20
10 1.98542621329309 -2.47559639334034 3.17340428422712 10
-1 -3.61948051533946 -1.18489808997859 3.80849349278123 -1
4 -2.0940045770826 -1.92803176917456 2.84642963584018 4
11 -3.375 4.375 5.52550902632509 11
-1 2.47896579998472 5.9762205702964 6.46996783163006 -1
-7 2.74448051533946 4.19010191002141 5.00890480199445 -7
-2 3.87961256380478 -2.07134405386938 4.3979381344821 -2