TK Solver Keeps On Working,
In Calculation, Programming, Knowledge Management

Talk to David Clay about TK Solver and he’ll probably begin by telling you about his most recent project: a model to calculate conversion of VHS video tapes to digital format— resolution, file size, and data transfer rates over various links, among other things.
“It took me less than two hours,” says Clay, a retired engineer from Rockford, Illinois. “There’s dozens of little places where TK fits in for doing that kind of stuff. I can’t get along without it!”
Talk to Clay a bit longer and you’ll hear an interesting story of the many ways TK helped him in a long career in aerospace and mobile hydraulics—from how it liberated him from coding FORTRAN to how, using it, he went beyond modeling and programming to knowledge management.
David Clay  
Home: Rockford, Illinois  
TK User Since: 1985  
Uses TK For: Engineering, boating, navigation, home finance  

“TK takes care of the input-output business,” Clay says. “When I wrote FORTRAN code in the 60s you spent three fourths of your time making the page into something you could read and the remaining one quarter actually doing any work. With TK you enter equations once and in any order, and the plotting and tables are almost instantaneous. You spend your time actually working the equations, doing what you want to do. TK took away all the wasted overhead and made the process much more efficient.”

This dovetails with Clay’s views on TK and knowledge management: “In an engineering department you have people from all different backgrounds—FORTRAN, BASIC, and so on—and if each works his own separate way, you don’t get any synergy. The usefulness of each person’s work stands on its own. With TK as a common working language, a department can build up a library. You’re only as good as your library; you can’t afford to reinvent the wheel every time.

“TK is very nicely set up to pull pieces in from other people’s work,” he says. “TK has features that allow you to manage on a corporate level—what things are going on, who’s using what. It lets a whole department work together, rather than everyone going off in different directions.”
Besides the one-time equation entry, plotting and table management, Clay cites TK’s comment management: “It’s so easy to document what you’ve done. I can say, ‘this equation came from the Internet, a textbook, or wherever’. Commenting is so easy in TK. You can keep track of where you got something—and whether you still believe it!”
In his career, Clay developed some 20 TK engineering models, ranging from a complete solenoid coil design to steady state models of sum of forces on a hydraulic valve spool. There are also some 20 “home” models, ranging over navigation, boating, and home finance.
“Most of my stuff in engineering has been quick solutions to quick problems—but if you do it on a hand calculator, then say ‘Oh I wish I’d changed one parameter’—it’s gone, so you wind up doing it a second or third time,” he says. “It’s so much easier to just drop it into TK, then you can change it tomorrow without re-entering the equations.
“And TK has the excellent backsolving capability,” Clay adds. “In engineering you frequently want to work backwards. You find that the constraints are different from what you first pictured: you put a constraint in and then backsolve.”
He says he uses Excel occasionally, “but I strongly discourage people from using it in engineering work, because of the difficulty of maintaining the engineering change control, documenting which equations you’re using, and so on. It can get to be spaghetti code in a hurry.
“With the TK Player available, I might use Excel a bit more,” Clay adds. “I like the idea of using Excel as a container for data, but I don’t like putting equations in it; I much prefer the concise, readable, documentable equations you have in TK.”