The discusser wishes to complement Dr. Kirk on his contribution to a very practical design analysis problem. Dr. Kirk has commented that he has avoided assembling his x{t) and y(t) time transient solution into a more convenient R(t) and f)(t) form. This was avoided, since there was an excessive chance for error in the algebraic manipulation. This discusser would like to point out that this fear is not necessary. The manipulation of these equations can be handled via FORMAC [14, 15], which is a

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... ormula manipulation computer language. This is available under PL/I compilers. This language has the capability of normal algebraic manipulation as well as differentiation. Integration is not allowed. Differentiation of R(t) with respect to any variable is possible. Thus , maximum response, i?(Omax, can be found easily and directly.