NAME FT - NMRPipe Fourier Transform SYNOPSIS nmrPipe -fn FT [-auto | -real | -bruk | -inv] [-alt] [-neg] DESCRIPTION FT applies a complex Fourier transform (FT) to produce a complex result. Options include selection of forward or inverse transform, negation of imaginaries before transfor- mation, and sign-alternation (negation of alternating points) of the data before transformation. An option to apply a complex FT to a real data sequence is also provided for TPPI mode data. FT options can also be selected automatically from the header, provided that acquisition mode information was recorded appropriately during conver- sion. OPTIONS -real This flag selects a complex Fourier transform for a real-only sequence. It is commonly used for data recorded in the TPPI mode. This option will reduce the data size by a factor of two. -alt This flag causes sign alternation to be applied to the data before the FT. In the case of complex data, sign alternation has the effect of exchanging the left and right halves of the corresponding spectrum: | nmrPipe -fn FT -alt \ is equivalent to: | nmrPipe -fn FT \ | nmrPipe -fn SHUF -exlr \ -neg This flag causes the imaginary part of the data to be negated before the FT. It is equivalent to reversal of the corresponding spectrum followed by a one-point right circular shift: | nmrPipe -fn FT -neg \ is equivalent to: | nmrPipe -fn FT \ | nmrPipe -fn REV -sw \ | nmrPipe -fn CS -rs 1 -sw \ -bruk This flag applies a sign-alternated real FT suitable for Bruker Sequential Mode (QSEQ) data. This option will reduce the data size by a factor of two. It is equivalent to: nmrPipe -fn FT -real -alt -auto This flag enables automatic selection of the FT modes. Inverse mode will be selected if the data are in the frequency-domain. Real transform mode will be selected if the acquisition mode is recorded as Real, TPPI, or Sequential (Bruker). Negation of imaginaries will be selected if the acquisition mode is recorded as Complex-N States-N, or States-TPPI-N. Sign-alternation will be selected if the acquisition mode is recorded as States-TPPI, States-TPPI-N, or Sequential (Bruker). -inv This flag selects an inverse Fourier transform. EXAMPLES The following is a basic 2D Fourier transform scheme for States, States-TPPI, or TPPI phase-sensitive data. Use of FT -auto will select the correct Fourier Transform type (real or complex), and if the acquisition modes were speci- fied correctly during conversion, it will also automatically select the proper sign-adjustment mode. nmrPipe -in test.fid \ | nmrPipe -fn SP -off 0.5 -end 0.95 -pow 1 -c 1.0 \ | nmrPipe -fn ZF -auto \ | nmrPipe -fn FT -auto \ | nmrPipe -fn PS -p0 0.00 -p1 0.00 -di -verb \ | nmrPipe -fn TP \ | nmrPipe -fn SP -off 0.5 -end 0.95 -pow 1 -c 1.0 \ | nmrPipe -fn ZF -auto \ | nmrPipe -fn FT -auto \ | nmrPipe -fn PS -p0 0.00 -p1 0.00 -di -verb \ -ov -out test.ft2 The following is a basic magnitude-mode 2D processing scheme; note that in this case, the imaginaries are not deleted after the first Fourier transform, and the magnitude calculation function MC is used after the second transform. Note also that the second FT is a complex one, which can be specified as "FT -neg" if the Y-Axis of the result needs to be reversed: nmrPipe -in test.fid \ | nmrPipe -fn SP -verb \ | nmrPipe -fn ZF -auto \ | nmrPipe -fn FT -auto \ | nmrPipe -fn TP \ | nmrPipe -fn SP -verb \ | nmrPipe -fn ZF -auto \ | nmrPipe -fn FT \ | nmrPipe -fn MC \ -out test.ft2 -verb -ov The following is a general 2D inverse Fourier transform scheme, which will regenerate a 2D hypercomplex FID from a real-only 2D spectrum. Note use of the generic nmrPipe option -ad to make room for hypercomplex data, and the use of the hypercomplex transpose option TP -hyper: nmrPipe -in test.ft2 \ | nmrPipe -fn HT -auto -verb \ | nmrPipe -fn PS -inv -hdr \ | nmrPipe -fn FT -inv \ | nmrPipe -fn ZF -inv \ | nmrPipe -fn APOD -inv -hdr -ad \ | nmrPipe -fn TP -hyper \ | nmrPipe -fn HT -auto -verb \ | nmrPipe -fn PS -inv -hdr \ | nmrPipe -fn FT -inv \ | nmrPipe -fn ZF -inv \ | nmrPipe -fn APOD -inv -hdr \ -out test.fid -ov