Letters to the editor: correction's to Stone's compiler procedures

Although the above errors are most likely typographical in origin, there is an omission which makes the program recurse to infinite depth upon encountering '( ' in the input string. When procedure "p r imary" is evoked and encounters '( ' it then evokes procedure "expression" without updating the position of the pointer in the input string. Hencewhen "pr imary" is again evoked, and encounters ' ( ' , the process is repeated. To correct this, I inserted a call to procedure " scan" between lines 61 and 62, which also eliminates the need to position the input pointer at the first character prior to calling procedure "express ion" initially. The algorithm was then coded in Raytheon 520 (recursive) Real-Time FORTRAN, and produced the correct answers to the examples given. JEFFREY L. DEVEBER