Hi Christian,
Thanks a lot. I was indeed looking for the outer product of a 3D
volume by a 1D vector. The multiple-call idea and avwmerge in a
shell-script is the solution. That, along with a quick matlab crash
course in order to relieve some of the pain ;-).
Rutger.
Quoting Christian Beckmann <[log in to unmask]>:
> Hi Rutger,
>
> not sure what you're trying to do - the _inner_ product of a 4D data
> set and a 1D vector gives you a 3D volume, this can be done using the
> GLM in FEAT, where 1D vector is the design and the 3D volume PE1 then
> is what you want.
> If you're looking for the _outer_ product of a 4D series and a 1D
> vector then nope, that can't be done using the avw tools. If instead
> you were thinking about creating the _outer_product of a 3D image by a
> 1D vector in order to create a 4D series then it's easiest to do this
> in matlab (we do supply i/o functions in $FSLDIR/etc/matlab !), though
> you can do this using multiple calls to avwmaths (one call per value in
> your 1D vector) followed by avwmerge -t . You could do this as part of
> a simple shell script but using matlab would save you a lot of pain ;)
> hope this helps
> Christian
>
>
> On 23 Jul 2007, at 22:02, Rutger Goekoop wrote:
>
>> Dear list,
>>
>> Is it possible to multiply 4D images by 1D vectors (such as 1 0 0 0 1 0 0 0
>> etc) e.g. using avwmaths, or do I need a mathematical tool like Matlab to do
>> this?
>>
>> Cheers,
>>
>> Rutger.
>>
>> Dr. R. Goekoop, MD, PhD.
>> Resident in Psychiatry
>> Parnassia Psychomedical Center
>> Clinical Centre for First Onset Psychosis
>> Paradijsappelstraat 2
>> 2552 HX Den Haag
>> Tel. 0031-6-52548515
>> Email: [log in to unmask]
>>
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> ____
> Christian F. Beckmann
> University Research Lecturer
> Oxford University Centre for Functional MRI of the Brain (FMRIB)
> John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.
> [log in to unmask] http://www.fmrib.ox.ac.uk/~beckmann
> tel: +44 1865 222551 fax: +44 1865 222717
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