The Use of Interactive Graphics To Solve Numerical Problems With the advent of on-line (time-sharing) computer systems and graphic terminals, we have available a new dimension in numerical problem solving capabilities. Rather than simply use the new power to achieve fast turnaround, we can develop interactive routines which are easy to use and also take advantage of the insight and visual capabilities of the human problem solver. Several on-line systems for general purpose mathematical problem solving have already been implemented as well as some special purpose systems for solving problems in a particular area such as ordinary differential equations. The advantage of restricting the problem area is that the interface with a user can be greatly simplified. In this paper we discuss some of the advantages accrued by such systems and design considerations for interactive routines. Furthermore, an implementation of an on-line least squares data-fitting program, PEG, is presented with results obtained from empirical data. In conclusion, area for future work in this field are discussed. CACM October, 1970 Smith, L. B. interactive graphics, computer graphics, graphics, least squares, data-fitting, interactive computing, on-line mathematics 1.3 3.1 5.13 5.5 CA701012 JB February 10, 1978 9:14 AM 1978 4 1978 1978 4 1978 1978 4 1978 1307 5 1978 1589 5 1978 1813 5 1978 1978 5 1978 1978 5 1978 1978 5 1978