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TwotenfitContent-type: text/html twotenfitSection: User Commands (1)Index Return to Main Contents NAMEtwotenfit - Fits two diffusion tensors to diffusion MRI measurements.SYNOPSIStwotenfit <data file> <scheme file> [-cylsym]DESCRIPTIONReads diffusion MRI data, acquired using the acquisition scheme detailed in the scheme file, from the data file. The data file stores the diffusion MRI data in voxel order with the measurements stored as big-endian four-byte floats and ordered as in the scheme file. See modelfit(1) for the format of the data file and scheme file. The program fits a pair of diffusion tensors to each voxel and outputs the results, in voxel order and as big-endian eight-byte doubles, to the standard output. The program outputs seventeen values in each voxel: [exitcode, ln(S(0)), m, a_1, D_1xx, D_1xy, D_1xz, D_1yy, D_1yz, D_1zz, a_2, D_2xx, D_2xy, D_2xz, D_2yy, D_2yz, D_2zz]. An exit code of zero indicates no problems. For a list of other exit codes, see modelfit(1). The entry S(0) is an estimate of the signal at q=0; m is the number of fitted components, which is always 2 here; a_1 is the mixing parameter of D_1, a_2 is that for D_2.By default, the program constrains the two diffusion tensors only to be positive definite. The program can also constrain the diffusion tensors to have cylindrical symmetry (two equal eigenvalues). This program is a simple interface to the program modelfit. The modelfit program provides more options for fitting pairs of diffusion tensors. If the first command line argument is - the program reads data from the standard input. EXAMPLESFit two positive-definite diffusion-tensors to the data in SubjectA.Bfloat:twotenfit SubjectA.Bfloat A.scheme > TwoTensorA.Bdouble Equivalently: cat SubjectA.Bfloat | twotenfit - A.scheme > TwoTensorA.Bdouble Fit two cylindrically symmetric positive-definite diffusion tensors: twotenfit SubjectA.Bfloat A.scheme -cylsym > TwoTensorA.Bdouble OPTIONS
AUTHORSDaniel Alexander <camino@cs.ucl.ac.uk>SEE ALSOmodelfit(1), dtfit(1), threetenfit(1), fa(1), trd(1), shfit(1), shanis(1)BUGS
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