System Matrices

For loading the system matrix, one could in principle again call measData but there is again a high level function for this job. Since system functions can be very large it is crucial to load only the subset of frequencies that are used during reconstruction The high level system matrix loading function is called getSystemMatrix and has the following interface:

function getSystemMatrix(f::MPIFile,
                         frequencies=1:rxNumFrequencies(f)*rxNumChannels(f);
                         bgCorrection=false,
                         loadasreal=false,
                         kargs...)

loadasreal can again be used when using a solver requiring real numbers. The most important parameter is frequencies, which defaults to all possible frequencies over all receive channels. In practice, one will determine the frequencies using the the Frequency Filter functionality. The parameter bgCorrection controls if a background correction is applied while loading the system matrix. The return value of getSystemMatrix is a matrix of type ComplexF32 or Float32 with the rows encoding the spatial dimension and the columns encoding the dimensions frequency, receive channels, and patches.