Valentin Albillo's HP Collection

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HP Calculators

HP Calculator Programs

For the historical record and in order to preserve my earliest and/or unreleased efforts in the wonderful world of HP programmable calculators and pocket computers, here you'll find a selection of HP programs I wrote for various HP models ranging in capabilities from the HP-25 to the HP-71B.

The HP-25 programs are for the most part (not all) quite simple affairs, written just for practice and never intended for release, as back in 1975 I was learning programming techniques (the HP-25 was my very first programmable calc) and the HP-25 was slow and had very little RAM (49 steps, 8 registers) as well as a very limited programming paradigm (no labels, no subroutines, no flags), so don't expect anything too sophisticated (though there are a few surprises). That said, I think they're still quite enjoyable and fun to check and even convert to run on other devices.

On the other hand, most subsequent HP models (such as the HP-11C, HP-67, HP-34C, HP-41C, etc., let alone the HP-71B !) had much more RAM for both programs and data and also advanced programming capabilities, so the programs I wrote for them take full advantage of that and are significantly more complex and capable, no longer "practice" ones. Some of them were published in the past in physical media (paper magazines, solution books, CD/DVD/USB pendrives), which would-be readers (even the authors themselves) had to pay for, but now for the first time they'll be available to download for free, as will existing but still unpublished programs or even new programs I might write now and in the foreseeable future. Stay tuned !

P.S.: All titles ending in (Full Scan) are part of my Project HAM.

PDF HP Program VA250 - HP-25 Programs (Album Anillas) (Full Scan)

(62 pages, 19,638,608 bytes, in Spanish with Notes in English)

This 62-page PDF document includes a selection of 40 programs I wrote for the HP-25 (my first HP calculator) back in 1975, which serve to demonstrate just how wonderful and capable the HP-25 was back then, and the sheer enjoyment of owning it, learning from it, and making the most out of it.

Besides the 40 programs themselves (completely documented with Theory, Usage, Examples and of course the Source code), a list with the titles of all programs both in Spanish and English is given in the included Notes (in English).

Caveat lector:

Note that in 1975 I was utterly on my own as far as HP calculators were concerned. I knew nothing about PPC, or users' clubs of any sort, nor any other HP-25 user. Thus, I developed all the programs here in isolation and documented them in my own handwriting and of course in Spanish, my native language, as they were not intended to be shared with anyone else. However, as all the programs are of a mathematical nature, this doesn't detract from their understandability or usability, by simply inspecting the equations and following the given Examples.

List of the 40 Programs for the HP-25 included in this document (60 pages in all):

      - Aritmética compleja: +, -, x, /, raiz n    (Complex Arithmetic)
      - Trigonometría compleja: sen(a+bi), cos(a+bi)    (Complex Trigonometry: sin, cos)
      - Evaluación de expresiones complejas    (Complex Expression Evaluation)
      - Evaluación de polinomios complejos    (Complex Polynomial Evaluation)
      - Trigonometría compleja: arcsen(a+bi), arccos(a+bi)    (Complex Trigonometry: arcsin, arccos)
      - Logaritmo y exponencial compleja    (Complex Logarithm and Exponential)

      - Evaluación polinómica: y=a1x6+a2x5+...+a5x2+a6x+a7    (Polynomial Evaluation)
      - Polinomio de colocación cúbico en puntos equiespaciados    (Cubic Polynomial Fit at Equally-Spaced Points)
      - Polinomio de colocación y=ax2+bx+c en puntos cualesquiera    (Cuadratic Polynomial Fit at Arbitrary Points)
      - Coeficientes para un polinomio de colocación    (Coefficients of a Polynomial Fit)
      - Evaluación de un polinomio de colocación    (Evaluation of a Polynomial Fit)

      - Ecuaciones x5+ax4+bx3+cx2+dx+e = 0    (Solving 5th-degree Equations)
      - Ecuaciones ax+bx2+cx+d = 0    (Solving ax+bx2+cx+d = 0)
      - Soluciones enteras para y2 = ax2+bx+c    (Finding Integer Solutions of y2 = ax2+bx+c)
      - Resolución de ecuaciones: Método de Newton    (Solving f(x)=0: Newton's Method)
      - Resolución de ecuaciones: Método iterativo    (Solving f(x)=0: Iterative Method

      - Integrales definidas: Método de Chebyshev    (Definite Integrals: Chebyshev's Method)
      - Derivación aproximada: cálculo de y'(x)    (Approximate Derivatives: y'(x))
      - Integrales definidas: Método de Gauss-Legendre    (Definite Integrals: Gauss-Legendre's Method)
      - Integrales definidas: Método de Gauss-Chebyshev    (Definite Integrals: Gauss-Chebyshev's Method)
      - Ecuaciones diferenciales: Método de Euler    (Differential Equations: Euler's Method)
      - Ecuaciones diferenciales: Método de Runge-Kutta (orden 3)    (Differential Equations: Runge-Kutta 3's Method)
      - Ecuaciones diferenciales: Método de R-K (orden 4)    (Differential Equations: Runge-Kutta 4's Method)
      - Derivación aproximada: cálculo de y"(x)    (Approximate Derivatives: y"(x))
      - Integrales definidas: Método de Runge-Kutta    (Definite Integrals: Runge-Kutta's Method)
      - Integración de funciones empíricas: Regla de Simpson    (Numerical Integration: Simpson's Rule, Discrete Points)
      - Ecuaciones diferenciales de 2º orden: y" = f(x,y)    (Differential Equations of 2nd Order: y" = f(x,y))
      - Integrales definidas    (Numerical Integration)

      - Funciones hiperbólicas: Sh x, Ch x, Th x, e inversas    (Hyperbolic Functions and Inverses)
      - Integral de logaritmo    (Logarithmic Integral)
      - Integrales de seno y coseno    (Sine and Cosine Integrals)
      - Integrales de Fresnel    (Fresnel Integrals)
      - Integral elíptica incompleta de primera especie    (Incomplete Elliptic Integral of the 1st Kind)
      - Integral de los errores    (Error Integral)
      - Distribución normal    (Normal Distribution)
      - Distribución normal inversa    (Inverse Normal Integral)
      - Factoriales exactos    (Factorial)
      - Combinaciones mCn    (Combination)
      - Permutaciones mPn    (Permutation)
      - Ajuste por mínimos cuadrados    (Linear/Log/Exp/Pow Regression)

PDF HP Program VA251 - HP-25 Solving 2nd-order differential equations

3-page paper featuring a 37-step RPN program for the HP-25 to numerically solve 2nd-order differential equations of the form y”=f(x,y) subject to initial conditions, using the 5th-order predictor-corrector Numerov’s method. One worked example included.

PDF HP Program VA252 - HP-25 Gamma Function and Factorials

2-page paper featuring a 49-step RPN program for the HP-25 to accurately evaluate the Gamma function in the interval [1, 2], as well as approximate factorials for real-valued x. Three worked examples included.

PDF HP Program VA340 - HP-34C Matematica Avanzada (with Notes) (Full Scan)

(78 pages, 26,854,844 bytes, in Spanish with Notes in English)

This HP-34C Solutions Book was created to enhance the sales of the then (1980) newly released HP-34C calculator, a fantastic advanced programmable RPN model, which was much more affordable than previous advanced models while providing a plethora of useful features both for using in manual calculations and for writing your own programs.

My friend Fernando del Rey and I set up to create a sufficient number of programs to be collected into a new Hewlett-Packard Spanish-language Solutions Book titled "HP-34C Matemática avanzada" (Advanced Math). In all, we created and submitted a grand total of 18 programs to HP but they selected for publication just the first 16 and the last two were excluded from the book. Now I've righted this wrong by including both at the very end of the scanned book, where you'll also find some interesting Notes (in English) on the back story of this HP-34C Solution Book and its 2021 scanning.

The book features the following 16+2 programs for the HP-34C (most will run with minor or no changes on the HP-15C):

            - CAMBIOS DE BASE (Base Conversions)
            - FACTORES PRIMOS, MCD, DECIMAL A FRACCION (Factorization, Least Common Divisor, Decimal to Fraction)
            - ECUACION DE 4º GRADO (4th-degree Polynomial Equations, also 3rd- and 2nd-degree)
            - SISTEMAS DE ECUACIONES: f(x,y) =0 and g(x,y) = 0 (Systems of two Non-linear Equations)
            - AREAS, LONGITUDES, VOLUMENES (Areas, Lengths of Arc, Volumes)
            - INTEGRALES DOBLES (Double Integrals)
            - SUMACION DE SERIES INFINITAS ALTERNADAS (Summation of Infinite Alternating Series)
            - ECUACIONES DIFERENCIALES : y'= f(x,y) (1st-Order Differential Equations)
            - SISTEMAS DE ECUACIONES DIFERENCIALES (Systems of two 1st-Order Differential Equations)
            - OPERACIONES CON NUMEROS COMPLEJOS (Complex-number Operations)
            - OPERACIONES VECTORIALES (Vector Operations)
            - DETERMINANTE, ECUACION CARACTERISTICA, AUTOVALORES DE MATRIZ 3x3 (3x3 Determinant, Characteristic Eq., etc.)
            - INTERPOLACION (Data Interpolation)
            - AJUSTE DE DATOS (Data Fitting)
            - ANALISIS ARMONICO (Harmonic Analysis)
            - RESOLUCION DE TRIANGULOS (Triangle Solutions)

Bonus programs:

            - TABLAS DE AMORTIZACION (Loan Amortization Schedule)
            - CALENDARIO (Date and Calendar Operations)

PDF HP Program VA341 - HP-34C Loan Amortization Schedule

2-page paper featuring a 70-step RPN program for the HP-34C to generate either a complete amortization schedule showing each period of a fully amortized loan or a partial schedule between two given periods. One worked example is included.

PDF HP Program VA342 - HP-34C Summation of Alternating Series

3-page paper featuring an 84-step RPN program for the HP-34C to quickly and accurately find the sum of infinite alternating series, even divergent ones (Euler sum). Three worked examples are included.

PDF HP Program VA343 - HP-34C Double Integrals

3-page paper featuring a 67-step RPN program for the HP-34C to compute the numeric value of a definite double integral of a user-specified f(x,y) between given limits. Four worked examples are included.

PDF HP Program VA344 - HP-34C Solving Quartic Equations

4-page paper featuring a 175-step RPN program for the HP-34C, HP-67 and HP-97 programmable calculators to compute simultaneously and non-iteratively all four real and/or complex roots of a general 4th-degree (or less) polynomial equation with real coefficients, using exact formulas. The HP-34C's SOLVE function is not used and all four real and/or complex roots are computed at once in 15-20 seconds at most.

It will also work in the HP-15C, the HP-41C series and posibly other RPN models with very minimal changes (detailed in the Notes). Four worked examples are included, solving three quartics and one cubic equation.

PDF HP Program VA345 - HP-34C Nonlinear Equations Systems

4-page paper featuring a 102-step RPN program for the HP-34C programmable calculator to solve a system of two arbitrary nonlinear equations in two variables. Will also work as-is in the HP-67/97 and in the HP-15C and HP-41C series with minimal changes. Two worked examples are included.

PDF HP Program VA346 - HP-34C Factoring-GCD-Decimal to Fraction

3-page paper featuring a 127-step program for the HP-34C programmable calculator to factorize an integer into its prime factors, compute the greatest common divisor (GCD) of two integers, and find integer fractions which best approximate a given real value. It will also work in the HP-41C series with trivial changes. Three worked examples are included.

PDF HP Program VA348 - HP-34C Memory Game and Trainer

3-page paper featuring an 86-step RPN program for the HP-34C to challenge your memory by testing your ability to remember what you’ve just seen and offering afterwards an accurate comment on your performance.

PDF HP Program VA411 - HP-41C Finding Roots of Equations

4-page paper featuring a 42-step RPN program for the HP-41C to find real roots of an arbitrary user-supplied equation f(x)=0 using Newton’s method and a user-given initial guess. Interactive and non-interactive versions provided. Five worked examples included.

PDF HP Program VA412 - HP-41C Finding Extrema of Functions

3-page paper featuring a 28-step RPN program for the HP-41C to find extrema (maxima and/or minima) of an arbitrary user-supplied function y=f(x) by calling program RF (Root Finder) internally as part of the computation. Two worked examples are included.

PDF HP Program VA413 - HP-41C 3-point Gaussian Integration

3-page paper featuring a 55-step RPN program for the HP-41C to evaluate the definite integral between given limits of an arbitrary user-supplied function f(x) using the fast 3-point Gauss-Legendre quadrature formula applied over a number of subintervals. Three worked examples included.

PDF HP Program VA414 - HP-41C Dice Rolling with Graphics

3-page paper featuring a 90/62-step RPN program for the HP-41C programmable calculator series to simulate randomly throwing two dice, which are printed graphically followed by their sum.

It includes a subroutine which can be globally called from other programs or from the keyboard to accumulate in the printer buffer the graphics for any single die face. Both Standard and Synthetic Programming versions are included.

PDF HP Program VA415 - HP-41C Systems of 1st-order Differential Equations

7-page paper featuring a 137-step program for the HP-41C programmable calculator to obtain quickly and accurately an approximate numerical solution for a system of N simultaneous first-order differential equations or, conversely, a single differential equation of the Nth-order, using a fourth-order Runge-Kutta method. It will also run in the HP-41CV, HP-41CX and the HP42S. Two worked examples included.

PDF HP Program VA416 - HP-41C Mate w King Bishop Knight Practice

7-page, 13-diagram paper featuring a 285-step program for the HP-41C programmable calculator (will also run as-is in the HP-41CV or the HP-41CX and with trivial changes in the HP42S as well as in compatible devices or emulators). The program is intended to help the user practice in order to achieve the difficult basic checkmate of King, Bishop and Knight (controlled by the user) vs. King alone (controlled by the program) within a specified number of moves. The user must try and checkmate before the allotted moves elapse while the program does its best to avoid being checkmated.

Two worked examples included, one of them against the world-class chess engine Stockfish 9 (released in 2018 and rated at more than 3,300 ELO), the other against a human user.

PDF HP Program VA417 - HP-41C Systems of Linear Equations - Gauss-Seidel

4-page paper featuring a 129-step RPN program for the HP-41C programmable calculator (will also run as-is in the HP-41CV/CX and in the HP42S with trivial changes) to obtain a numerical solution for a system of N algebraic linear equations in N unknowns using the iterative method of Gauss-Seidel, a relaxation/overrelaxation method.

A system of up to 15 equations can be solved if using all 4 memory modules (HP-41C) and the input matrix is left unchanged by the procedure so it can be reused for further processing. Also, full details are given to modify it to use synthetic instructions to save registers, if desired. Two worked examples included.

PDF HP Program VA418 - HP-41C Memory Game and Trainer

3-page paper featuring a 142-step fun game RPN program for the HP-41C to challenge your memory by testing your ability to remember what you’ve just seen and offering afterwards an accurate comment on your performance.

PDF HP Program VA419 - HP-41C ESP Tester

2-page paper featuring an 85-step fun RPN program for the HP-41C to test your “ESP” (Extra-Sensorial Powers) by conducting a series of 10 tests, after which it reports the % of success and an evaluation of your alleged extrasensorial abilities (if any). One sample run included.

PDF HP Program VA420 - HP-41C Eigenvalues of Symmetric Matrices - Jacobi

5-page paper featuring a 215-step RPN program for the HP-41C programmable calculator (will also run as-is in the HP-41CV/CX and in the HP42S with trivial changes) to find all eigenvalues of a real symmetric NxN matrix using the iterative method of Jacobi, which is fast and always converges.

Matrices up to 22x22 can be treated and full details are given about the algorithm and on how to modify the program to use synthetic instructions to save registers, if desired. One worked example and two test cases with solutions included.

PDF HP Program VA421 - HP-41C NxN Matrix Inversion

4-page paper featuring a 170-step RPN program I wrote in 1980 for the HP-41C programmable calculator (will also run as-is in the HP-41CV/CX) to compute the inverse of a real NxN matrix (no Advantage module back then), where N ranges from 1 up to 16, using a non-gaussian interchange method.

The program is written so that zero pivots will cause no trouble, they’re skipped and the following pivot is tested. The locations of all zero pivots are remembered and their corresponding interchanges are performed later.

PDF HP Program VA425 - UPLE - HP-41C Sistemas de Ecuaciones Diferenciales (Full Scan)

(9 pages, 3.232.120 bytes, in Spanish)

Program Submittal to the HP Users' Program Library Europe.
Este programa utiliza un metodo de Runge-Kutta de orden 4 para hallar una solucion numerica aproximada de un sistema de N ecuaciones diferenciales de primer orden. Alternativamente, tambien resuelve una ecuación diferencial de orden N. El valor de N solamente está limitado por la memoria disponible.

PDF HP Program VA426 - UPL 11019 - HP-41C Reversi (Full Scan)

(14 pages, 3.613.936 bytes, aka Othello)

Program Submittal to the HP Users' Library (Corvallis).
This program allows the user to play a game of Reversi (also known as Othello) against the HP-41C. The present program includes all features required, plays quite well and will easily defeat a beginner. The program itself runs the same with or without a printer, but if one is present, it will print the board.

PDF HP Program VA427 - UPL 00929C - HP-41C Chess 5x5 (Full Scan)

(20 pages, 2,907,464 bytes)

Program Submittal to the HP Users' Program Library (Corvallis).
This program challenges the user to play chess against the 41C in a 5x5 board, each player having King, Queen, Bishop, Knight, Rook and 5 pawns.

All standard rules are implemented, including pawn promotion. Full graphic capabilities, prints the board if printer is present. Includes 4 pages with barcode.

PDF HP Program VA428 - UPL PS - HP-41C Othello (00903C) (Full Scan)

This is my original submittal to the Hewlett-Packard Users' Program Library (USA) of my HP-41C program Othello at the request of HP UPL's Sandy Canning. Besides my original submittal, I've also included here four pages of good-quality barcode to allow for fast, error-free entry of the long program into the calculator using the wand.

This program allows you to play a game of Othello (aka Reversi) against the HP-41C. You can select who moves first and the opening. The 41C can play for you, even against itself. If a printer is present, the board is (optionally) printed. Includes Notes.

PDF HP Program VA430 - HP-41C Ruleta (Full Scan)

(14 pages, in Spanish)

Back in 1981 I was creating paid-for custom programs on demand. One day a customer called in with an unusual programming request: he wanted me to implement a system of his own creation to try and win at the roulette, as the casino accepted the use of calculators while betting.

Though at first I was puzzled, he was actually quite serious, the wealthy owner and CEO of a medium-sized company, with a penchant for such things. We met at a renowned restaurant and he told me all about his system, which seemed complex but doable. He agreed and bought an HP-41C plus card reader and four RAM modules, so I set to the task. Includes Notes in English.

PDF HP Program VA670 - HP-67 Programs (Cuaderno ICAI) (Full Scan)

(86 pages, 72,890,952 bytes, in Spanish with Notes in English)

This 86-page PDF document preserves a notepad (Cuaderno ICAI) in which I recorded and documented about 30 of my best programs for the HP-67, complete with Listings, Theory where necessary, usage Instructions and worked Examples aplenty. Additionally, it also includes assorted topics I indulged in at the time and which I addressed with my HP-67, such as worked numerical analysis problems, mathematical topics, runs of other programs, numerical data-fitting experiments and miscellanea.
The contents are (including Notes in English, with the English Abstracts for all files) :

Cuaderno ICAI: (30 programs, plus additional interspersed non-programs)

      - Super-Ellipse board for a 67/97 Games Pac racing game   (Hand-drawn, shows a completed game)
      - Captura del Klingon   (Klingon's Capture game; damaged listing)
      - Ajuste de un polinomio de 5º grado a Γ(x)   (5th-deg. polynomial fit to Γ(x))
      - Ajustar un polinomio adecuado a integral de Fresnel   (Polynomial fit to Fresnel Sine Integral)
      - Ejemplo de ajuste de una función de 2 variables independientes   (Sample fit to a 2-variable function)

      - Ajuste mini-max de y=ax2+bx+c a Γ(x)   (Mini-max fit of ax2+bx+c to Γ(x))
      - Ajuste por mín.cuad de polinomio de 4º grado a e^((x+1)/2)   (4th-degree polynomial fit to e^((x+1)/2)
      - Ajuste de funciones: Inversa de Γ(x)   (Function fit to Inverse Γ(x))
      - Inversa de una matriz 4x4   (Matrix Inverse 4x4)
      - Sistema de ecuaciones 7x7   (System of linear equations 7x7)

      - Hallar un mínimo de Γ(x) entre 1 y 2   (Find a minimum of Γ(x) in [1,2])
      - Polinomio de colocación grados 2,3,4   (Polynomial fit, degrees 2, 3, 4)
      - Números primos y factorización   (Prime numbers and factorization)
      - Resolución de f(z)=0 por Newton (z complejo)   (Roots of f(z)=0 for complex z)
      - Ecuación de 4º grado: ax4+bx3+cx2+dx+e=0   (4th-degree equation)

      - Parábola de mínimos cuadrados: y=a+bx+cx2 o y=e^(a+bx+cx2)   (Least-squares parabola or e^parabola)
      - Polinomio cúbico de mín. cuadrados: y=a+bx+cx2+dx3   (Least-squares cubic polynomial)
      - Regresión lineal de 2 variables: z=a+bx+cy   (Two-variable linear regression))
      - Cambios de base   (Base conversions)
      - Ejemplo de problemas de contorno: y"=xy, y(0)=0, y(1)=1   (Sample boundary value problem: y" = xy)

      - Problemas de contorno: y"=x2+y2, y(0)=0, y(1)=1   (Bounday value problem)
      - Polinomio de 3º grado mini-max   (3rd-degree minimax polynomial)
      - Ajedrez   (Chess - all White pieces vs. Black King)
      - Inversión de series de potencias: y=a1x + a2x2 +...+ a6x6   (Series reversion)
      - Newton - Sistemas f(x,y) = 0, g(x,y) = 0   (Systems f(x,y)=0, g(x,y)=0 by Newton's Method)

      - El buscador, el tesoro y el monstruo   (Treasure-hunt game)
      - Análisis de funciones: raices, graficación, etc.   (Function Analysis: roots, graphing, etc.)
      - Método de Bairstow: raices de polinomios grado N≤8   (Polynomial roots (deg.≤8), Bairstow Method)
      - Bridge-it   (Bridge-it game)
      - Polinomio osculador cúbico: y=a+bx+cx2+dx3   (Cubic osculating polynomial)

      - Raices de y(x)=0 (Iterativo, Newton, Cúbico, Parcial)   (Roots of y(x)=0 by four different methods)
      - 3x3 operaciones matriciales en cadena   (Chained 3x3 matrix operations)
      - Funciones elípticas de 1ª especie (φ,u,sn,cn,dn,inversas)   (Elliptic functions of the 1st kind & inverses)
      - Funciones especiales (7 funciones)   (7 Special functions: Bessel, Elliptic, etc.)
      - Regresión lineal de 2 variables: aplicaciones   (2-variable linear regression: applications)

      - Análisis de inversiones, Valor Presente Neto, Amortizaciones   (Net Present Value, Mortgage Loans, etc.)
      - Mate con rey, alfil y caballo   (Checkmate with King, Bishop and Knight)
      - Sistemas tridiagonales NxN (N≤12)   (Tridiagonal linear systems NxN, N≤12)
      - Cálculo de integrales dobles   (Double integrals)
      - Inversa de una matriz NxN (N≤5)   (NxN Matrix inversion, N≤5)

      - Ajedrez: mate con rey, alfil y caballo   (Checkmate with King+Bishop+Knight vs. K)
      - Series de Fourier - Análisis armónico - Datos discretos   (Fourier Series, Harmonic Analysis, discrete case)
      - Juego de los barcos   (Battleship game)
      - Aproximaciones racionales: y=(a0x2+a1x+a2)/(x2+b1x+b2)   (Rational approximations)

PDF HP Program VA672 - UPLE - HP-67 Integrales Dobles (Full Scan)

(8 pages, 3.106.463 bytes, in Spanish)

Program Submittal to the HP Users' Program Library Europe.
Versión española del programa #60376D. Calcula la integral doble de una f(x,y) dada entre limites arbitrarios x0,xm,yo,yn, utilizando un metodo que da valores exactos si f(x,y) es un polinomio de grado 3 (o menos) en x, y y muy buenas aproximaciones en todo caso.

PDF HP Program VA673 - UPLE - HP-67 Sumacion Series Infinitas Alternadas (Full Scan)

(8 pages, 3.424.258 bytes, in Spanish)

Program Submittal to the HP Users' Program Library Europe.
Version española del programa #60582D. Dada una serie infinita alternada cuyo termino general es definido por el usuario, el programa calcula rapidisimamente su suma. Implementa dos metodos: la transformacion de Euler y la transformacion de Hutton. Es posible tratar series divergentes.

PDF HP Program VA674 - UPLE 80006 - HP-67 El Juego de los Barquitos (Full Scan)

(11 pages, 6.476.367 bytes, in Spanish)

Program Submittal to the HP Users' Program Library Europe.
Este programa (a variant of Battleship) permite al usuario jugar con su HP-67/97 al Juego de los Barquitos. El juego se lleva a cabo en un "mar" 10x10 en el cual la calculadora dispone al azar un cierto numero de barquitos de diversos tamaños. El usuario debe tratar de hundirlos especificando las coordenadas del punto al cual dirige su disparo.

PDF HP Program VA676 - UPLE 52206 - HP-67 A Chess Game (Full Scan)

(7 pages, 1,232,242 bytes)

Program Submittal to the HP Users' Program Library Europe.
This program will allow you to play chess against the HP-67/97. Here the calculator plays the 16 White pieces and you have only the Black King. The initial position is the standard one and in order to win the calculator has to checkmate your King in 6 moves or less, else you'll be declared the winner.

PDF HP Program VA678 - UPLE 60377 - HP-67 Fourier Series - Harmonic Analysis (Full Scan)

(7 pages, 3,603,904 bytes)

Program Submittal to the HP Users' Program Library Europe.
The program will compute up to 9 coefficients of the Fourier Series (harmonics) to fit N given equally spaced data points (up to 19) which are samples from a periodic function. The program also computes the sum of squared errors for each k, as well as the mean value.

PDF HP Program VA680 - UPLE 60453 - HP-67 Elliptic Lowpass Filter Design (Full Scan)

(10 pages, 723,334 bytes)

Program Submittal to the HP Users' Program Library Europe.
This program is intended as a help when designing elliptic lowpass filters (or highpass, bandpass, bandstop once they've been transformed into a normalized lowpass). It will find the minimum degree of an elliptic lowpass filter that meets the standard requirements Amin (minimum stopband loss), Amax (maximum passband loss), FB (upper passband edge), FH (upper stopband edge).

If the degree N is <=30, the program also finds the zeros & poles of attenuation, and can also find the loss at any desired frequency, either manually or automatically. If you prefer an automatic plot, there's a choice between linear or logarithmic sweep.

Also, the routines for computing the Complete Elliptic Integral of the First Kind, the Complementary Elliptic Integral of the First Kind and the Elliptic Sine sn(u,k) can be executed from the keyboard without disturbing the computed zeros & poles.

PDF HP Program VA682 - UPLE 60454 - HP-67 Factors of a Number Fastest Program (Full Scan)

(7 pages, 2,674,192 bytes, scanned by Fernando del Rey)

Program Submittal to the HP Users' Program Library Europe.
This program will find all prime factors of a positive integer N, using a fast and efficient method to test if a number is a prime or to find its prime factors.

PDF HP Program VA684 - UPLE 60534 - HP-67 Areas Lengths Volumes Surfaces Rev (Full Scan)

(7 pages, 582,109 bytes)

Program Submittal to the HP Users' Program Library Europe.
Given a user-defined function which represents the equation of a 2-dimensional curve, either in rectangular or polar coordinates, this program can find the area bounded by the curve, the length of arc, and the area and volume of the solid of revolution generated by the curve when revolving around the X axis.

Routines for integration and derivation are included, as is an automatic sweep to evaluate the function. 8 excellent examples included.

PDF HP Program VA686 - UPLE 60535 - HP-67 Numerical Analysis of Functions (Full Scan)

(7 pages, 4,065,433 bytes)

Program Submittal to the HP Users' Program Library Europe.
Given a user-defined function y(x), this program can compute y(x), y'(x) and y"(x) for a given x, the definite integral of y(x) between limits [a, b] or [a, Infinity], a root of y(x)=0 or y'(x)=0, and automatically tabulate y(x) for a given range of x values, for plotting purposes for instance.

PDF HP Program VA688 - UPLE 60582 - HP-67 Summation of an Infinite Alternating Series (Full Scan)

(7 pages, 572,330 bytes)

Program Submittal to the HP Users' Program Library Europe.
This program computes very quickly the limit of the sum of an user-defined infinite alternating series, which is most useful in cases where the convergence is rather slow. It implements both Euler's and Hutton's transformations. Divergent series can be treated as well. 6 nice examples included, with timings and comments.

PDF HP Program VA710 - HP-71B Producing Digits of Pi one at a time

PDF HP Program VA711 - HP-71B Exact Integer Determinants and Permanents

PDF HP Program VA712 - HP-71B Multiprecision E and its roots

PDF HP Program VA713 - HP-71B Packing Long Integers

These articles, programs, pictures, their descriptions and other materials created by me are (c) Valentin Albillo, and can be used freely for non-profit purposes as long as (1) the contents aren't modified in any way and (2) the copyright is acknowledged. In plain words, you can download them and use them for non-profit purposes but do not include them in any media and/or site for which you're asking money, do not tamper with their contents and do not say or imply that you created them or that you don't know who created them, you must always give due credit to me.