Casio fx-3500P

Datasheet legend
Ab/c: Fractions calculation
AC: Alternating current
BaseN: Number base calculations
Card: Magnetic card storage
Cmem: Continuous memory
Cond: Conditional execution
Const: Scientific constants
Cplx: Complex number arithmetic
DC: Direct current
Eqlib: Equation library
Exp: Exponential/logarithmic functions
Fin: Financial functions
Grph: Graphing capability
Hyp: Hyperbolic functions
Ind: Indirect addressing
Intg: Numerical integration
Jump: Unconditional jump (GOTO)
Lbl: Program labels
LCD: Liquid Crystal Display
LED: Light-Emitting Diode
Li-ion: Lithium-ion rechargeable battery
Lreg: Linear regression (2-variable statistics)
mA: Milliamperes of current
Mtrx: Matrix support
NiCd: Nickel-Cadmium rechargeable battery
NiMH: Nickel-metal-hydrite rechargeable battery
Prnt: Printer
RTC: Real-time clock
Sdev: Standard deviation (1-variable statistics)
Solv: Equation solver
Subr: Subroutine call capability
Symb: Symbolic computing
Tape: Magnetic tape storage
Trig: Trigonometric functions
Units: Unit conversions
VAC: Volts AC
VDC: Volts DC
Years of production: 1980  Display type: Numeric display  
New price:   Display color: Black  
    Display technology: Liquid crystal display 
Size: 5½"×3"×½" Display size: 10+2 digits
Weight: 4 oz    
    Entry method: Algebraic with precedence 
Batteries: 2×"LR-1130" button cell Advanced functions: Trig Exp Hyp Lreg Intg Ab/c Cmem 
External power:   Memory functions: +/-/×/÷ 
    Programming model: Fully-merged keystroke entry 
Precision: 11 digits Program functions: Cond  
Memories: 7 numbers Program display:  
Program memory: 38 program steps Program editing:  
Chipset:   Forensic result: 9.0000157179  

fx3500p.jpg (29298 bytes)Here's yet another low-end Casio programmable calculator with a typical complement of functions: 38 program steps, 7 memory registers, a simplistic programming model, and a base set of scientific functions.

Limited as the programming model might be, Herman van Elburg, proud owner of a similar machine, taught me that it can still be used efficiently. And recently, Robert H. Windschitl wrote to me about an algorithm that minimizes the number of keystrokes needed to compute the Gamma function with good precision using Stirling's approximation. The result is the following programming example, which computes the logarithm of the Gamma function to 8+ digits of accuracy for any real argument:

Kin 2
Kin- 1
Kin+ 2
Kout 2
Kin- 1
Kout 2
Kout 2
Kout 2
Kout 2
X-K 1