The Equation Library Card has six applications:
1. EQLIB : Equation Library
2. PRTBL : Periodic Table of the Elements
3. COLIB : Constants Library
4. FIN : Finance
5. MES : Multiple Equation Solver
6. UTILS : Utilities
A few notes:
1. EQLIB contains EQNLIB, the actual library of equations arranged in a
scrolling menu list by subject, plus SOLVEQN, a way of using the equation
library in a program. The equation library works by invoking the multiple
equation solver on the selected set of equations.
2. The Periodic Table allows you to look up elements by symbol, by atomic
number, or visually by position in the table (using the cursor keys) and
retrieve a wealth of information (mass, density, melting point, boiling point,
atomic radius, you get the idea). A function PTPROP is available for doing
lookups under program control.
3. The Constants Library offers a scrolling list of constants ordered by name,
so that you can fetch the value of any constant (complete with units, of
course), to the stack. There is also a function CONST, suitable for use in
programs. For example, 'CONST(g)' evaluates to 9.80665_m/s^2, the acceleration
due to gravity. The equation library makes extensive use of this feature.
4. The financial application handles TVM (time value of money) calculations and
amortization schedules. Again, you can use these features interactively or
under program control.
5. The multiple equation solver is similar to the built-in SOLVR application,
except that it deals automatically with sets of equations. You set up the
equations and define some variables, then tell it to solve either for a single
variable or for all unknowns. The application automatically cycles through the
set of equations, looking for one that contains only a single unknown. It
solves for that, then continues the process until the requested variables are
solved for, or until it is unable to make further progress (you can prevent the
latter occurrence by being careful about how you set up the equations). A most
impressive display, especially when you say to "solve for h" and the calculator
automatically solves for several intermediate variables before finally finding
h. The easy way to set up the equations is to find the ones you want in the
equation library. Setting up your own custom equations is a bit unwieldy, but
it can be done. You can have a different set of equations set up in each
directory.
6. The utilities section contains the MINEHUNT game (which is every bit as
addicting as everyone says), plus a few extras: some user-defined units, an
alternate way of dealing with temperature gradients, and a few functions.
Dave Seaman