Blit is a highly efficient linear solver library designed for solving large-scale systems that arise from many medical imaging applications. Compared with the traditional solvers which solve for only one solution at a time, blit solvers can produce multiple solutions in a single call, thus is significantly faster. Blit uses iterative algorithms that support multiple right-hand-sides, referred to as the block solvers. A block solver handles the following equation: A [x_{1} x_{2} x_{3} ... x_{M}]=[b_{1} b_{2} b_{3} ... b_{M}]
where A is an N-by-N sparse (or full) matrix with either real or complex values, b_{i} and x_{i} are the right-hand-side and solution vectors, respectively.