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Thanks, good point Saad. Grade 10 math! On Thu, Dec 9, 2010 at 12:00 PM, Saad Jbabdi <[log in to unmask]> wrote: > you can do the raising using fslmaths and the fact that x^a = exp(a*log(x)) > make sure the numbers stay in a reasonable range though. > > Saad. > > > > > On 9 Dec 2010, at 16:56, Graeme Schwindt wrote: > > Hi Thomas, > > The EAR equation requires raising images to the the value of a constant, > 1.6075... > > I'm using Jimmy Shen's NIFTI toolbox ( > http://www.mathworks.com/matlabcentral/fileexchange/8797-tools-for-nifti-and-analyze-image) > to load the eigenvalue images in, perform the element-by-element arithmetic, > and write it out. FSLview will display the resulting images fine, but any > attempt to register them, or even downsample them using an identity > transformation produces an empty result... > > > On Thu, Dec 9, 2010 at 11:47 AM, Thomas Ballinger < > [log in to unmask]> wrote: > >> You could certainly multiply repeatedly with fslmaths - I don't know the >> formula for EAR, but if it's so complicated that you need an command that >> takes an arbitrary power of each voxel of an image, we could write a wrapper >> for fslmath calls that does this. >> >> I would also be curious about the registration problems, no suggestions >> there. What Matlab library are you using to write the output nii file? >> >> Thomas Ballinger >> RA at PNL at BWH >> >> >> On Thu, Dec 9, 2010 at 11:13 AM, SUBSCRIBE SPM Anonymous < >> [log in to unmask]> wrote: >> >>> Hi everyone, >>> >>> I'm also attempting to calculate this EAR value, but it appears fslmaths >>> does not have a 'power' option to raise an image to an arbitrary power, >>> aside from squaring the image. Am I missing something? >>> >>> I've written a script in matlab to perform the operation, but while fsl >>> will display the resulting NIFTI images, after any registration attempts it >>> creates a volume with all 0's. >>> >>> Would be curious if anyone has successfully calculated these images and >>> analysed them with tbss_non_FA. >>> >>> Thanks, >>> Graeme >>> >> >> > > > -- > Graeme C. Schwindt, HBSc > MD/PhD Student > University of Toronto > [log in to unmask] > > > -- > Saad Jbabdi > University of Oxford, FMRIB Centre > > JR Hospital, Headington, OX3 9DU, UK > (+44)1865-222466 (fax 717) > www.fmrib.ox.ac.uk/~saad <http://www.fmrib.ox.ac.uk/%7Esaad> > > > > > > > > > > > -- Graeme C. Schwindt, HBSc MD/PhD Student University of Toronto [log in to unmask]