The case for routine analysis of engineering problems by digital computers is now firmly proven. Programming in terms of the special semi-mathematical codes now available for large computers is particularly suited to the needs of engineers who are not professional programmers. In fact, for development work such as that described in the paper, the engineer with his knowledge of the physical significance of the mathematical expressions involved, has a considerable advantage.The authors describe their experience in the digital solution of two of the main problems encountered in power-system analysis, namely load-flow and short-circuit investigations. Use has been made of matrix algebra in combination with iterative methods, and the techniques evolved, which have been proved commercially feasible, are set out, with an indication of possible future developments.