## Group Bydder

Group Description ```MRI reconstruction matrices from Mark Bydder, UCSD. Note that that A is sparse and rectangular, and b is complex. Added March, 2006. -------------------------------------------------------------------------------- Excerpts of description, from email: -------------------------------------------------------------------------------- Inside there is a matrix A and a RHS vector b. Usually we want to solve Ax=b, for example x = lsqr(A,b,0,10) uses conjugate gradient on the normal equations to give an approximate answer. The data b are Fourier coefficients at arbitrary locations (in this case, in a spiral trajectory) and the matrix interpolates these data onto a regular grid suitable for FFT. So it's like non-uniform FFT. Please let me know if you find this matrix helpful or want to try some other (similar) matrices, eg. with radial trajectories. -------------------------------------------------------------------------------- The matrix I sent derives from a technique called regridding - a process of interpolating data at arbitrary locations onto an equally spaced grid. Eg. we sample a function f at two points 0
Displaying all 2 collection matrices
Id Name Group Rows Cols Nonzeros
1317 mri1 Bydder 65,536 147,456 589,824
1318 mri2 Bydder 63,240 147,456 569,160