sci Cilk is a language for multithreaded parallel programming based on ANSI C. Cilk is especially effective for exploiting dynamic, highly asynchronous parallelism, which can be difficult to write in data-parallel or message-passing style. Cilk provides an effective platform for programming dense and sparse numerical algorithms, such as matrix factorization and N-body simulations. Cilk is algorithmic, in that the runtime system employs a scheduler that allows the performance of programs to be estimated accurately based on abstract complexity measures.