I was bored and found a HP-27S

[Katie Wasserman]

(06-10-2014 11:18 AM)Don Shepherd Wrote:  In my opinion, one of HP's greatest achievements was the inclusion of programming constructs such as IF, sigma (loop), and L() and G() in the solver found in several calculator models, including the 27s. This made the solver more than just an equation solver; it is a real minimum programming language.

HP should have received some type of award for this solver, but we are all beneficiaries.

If I recall correctly the HP "step-by-step" publication called HP-27S/19B Technical Applications introduced L(), G() and other solver techniques. This was available when the 27S and 19B were first released. It showed how you could use the solver to compute coordinated transforms, solve linear equations, do complex variable arithmetic, find GCD and factor prime among other things. Pretty amazing for a "non-programmable" calculator.