who uses programmable calculators?


I know students do, but do any professionals use programmable calculators at their jobs any more?


Me. :-D

Seriously though, a lot of the engineers (~35%) that sit near me still have a calc on the desk for quick calculations. Most the finance/business people have one also (~50%).


Edited: 17 June 2013, 4:48 p.m.


All the time. It's much quicker and more convenient than the PC, and the programs I've written that I use frequently have been in it for 25 years continuously. (Although they've had improvements, I have not even had to reload them, modify them for a new OS, move them to new computers every few years, etc..)

Edited: 17 June 2013, 4:47 p.m.


Yes, I use my HP15C at work regularly.


I have three 42S's at the ready. One in the computer bag, one in the car (I do a lot of work over the phone) and one at my desk. They all have the same solver programs for things I do everyday and the formulas that I can never remember...


Three, first model HP 42s callculators. Two loaded with the exact same programs that assist with survey calculations, horizontal and vertical curve calculations, grading type problem solutions, etc. One of these has had the screen cancer in the lower left corner for about 7-years, but it hasn't reached any of the numbers yet.

the third one sits mostly unused as back-up.


Yes, I use a number of 50g programs all day every day as a software engineer. Only myself and an operations guy out of 100 or so people still use one though.

Mine gets used daily to project algorithm efficiency using regression models, check roundings in my code, do basic algebra stuff I can't be bothered to do myself, create truth tables from expressions for test cases and usual basic math operations.

At home it also does my finances, tax return, fuel projections, unit conversions for cooking (cups->ml etc), gets used for DIY measurement calculations (trig, 2d/3d geometry) and has various decision making roles, for example to stop the kids arguing over who's turn is it:

\<< RAND .5 < "CHILD 1" "CHILD 2" IFTE \>>

Currently trying to get it to talk to a Garmin GPS so I can use it for Geocaching as well.

Also working on a program which knocks out a bill of materials for building yurts.

There are never ending uses.

And most importantly, none of them lead to any Internet-related distractions.

Edited: 17 June 2013, 5:48 p.m.


I said *programmable*.

What *programs* do you need to run?


Probably my most often run program on my HP 50g is a simple thing doing no more than two divisions, two subtractions, and some stack manipulation. I use it quite often, but I don't *need* it any more than I *need* to drive to work (instead of walking).

Probably my second-most often used program on the same 50g is a simple thing: << / >> but I never *run* it. It's used as an argument to DOSUBS.

Still, I'll admit my programmable calculators are used more for recreation than for work.


I have the binomial PDF and CDF and the Poisson PDF and CDF programmed into my 11C, as I often teach statistics.

Also I often give students a "project" about saving for retirement based on their current age, so I program the calculations into my 12C to run the calculations for each student separately.


Only the basic math ops are not programs. Perhaps I should have been more clear. List of commonly used programs for me. I will provide listings when I am not embarrassed about how naff my RPL is.

ROLLD6 - Roll die.

FLIP - Flip coin.

TT - Dump truth table for expression.

PROJ - Project algorithm efficiency (wrapper around menu 96)

GAC - NMEA GPS data logger

FIN(plus various extensions) - financial / budget

FCALC - Fuel / journey / vehicle efficiency calculator

YURT - Yurt design / BOM tool.

EE/(various) - various EE shortcut programs, mainly for decomposing problems.

KANDA - Rounding checker (fuzzes expressions using know seed and PRNG, which is then compared to Java output).

MCA(various) - Monte Carlo / stochastic modelling tool, now a production application for my company.

CUPS - Program for my wife to convert US measurements to metric for cooking etc

SPRNG - Random number generator automatically seeded by system ticks.

Plus some more... :)

I probably wouldn't get half of this done on an RPN calc to be honest. RPL is far higher level.

Edited: 18 June 2013, 4:00 a.m.


At home? Just for fun only. At work? Yes, once in a while (about once all 4 years). The last 'program' was on a HP17bii+


to 'play' with the figures for risk provisioning. It was cheaper to get an HP17B2+ than programming it on excel.

A sad story compared with the programs I did as student.



I said *programmable*.

What *programs* do you need to run?

You asked who uses a programmable calculator, not who runs programs on his programmable calculator ;)

I use my 15C and WP34s at work regularly. But hardly ever need to run a program. Maybe once a year I write a quick program to safe myself some typing - nothing fancy.
However there is one program I have on the PC that I need to write for the calculator at some point.
For a given ratio it calculates the two resistor values from the e24 series that best match the ratio. On the calculator I would extend this a little to also include other e-series.

At home I write a program every now and then just for fun. I mainly use the HP65 or HP97 for that, because I can then store the program on a card.


I sometimes do, but my use is mostly for fun.


Yes, I wrote several programs for my FX-50FH (sorry, it's a Casio! :P) to help my students 'cheat' in the internal and public exams.

Edited: 17 June 2013, 11:34 p.m.


I am a professional civil engineer with 33 years of experience. I use my HP-42S every day and sometimes my HP-48G+ or my HP-41CX. I also use emulators for these three on my home PC, my work laptop, and my iPhone.

I don't program as much as I used to, but I still write programs from time to time. I really like the interchangeable solution type of program for single equations that originated with the HP-65 IIRC. It is usually faster than a SOLVER routine, can handle a higher level of sophistication in the program, and the results can be properly annotated. On the other hand, the programs are much longer.

On my HP-42S I have the following programs:

HW: This is an interchangeable solution to the Hazen-Williams equation for pressure flow in a pipe with an overlapping interchangeable solution to the Continuity Equation. I first wrote this for the HP-41CX back in 1982 when my wife was getting an ultrasound with our first child. I have a similar program for the Mannings Equation for pressure flow, but only an HP-41CX version.

CANAL: This is an interchangeable solution to the Mannings Equation for open channel flow in a triangular, rectangular, or trapezoidal channel. This also started life on the HP-41CX. I use the same subroutine for solving for normal depth and bottom width, with a flag determining which variable to solve for.

SD & SEWER: This is an interchangeable solution to the Mannings Equation for open channel flow in a pipe. This program has two entry points, one for storm drain pipes (uses cfs for the flow rate) and one for sewer pipes (uses gpm for the flow rate). This program includes a solver subroutine for finding the angle from the top of the free surface to the invert of the pipe.

HYDR: This is a multi-menu step-by-step solution for single basin hydrology using the Rational Method. The first step is entering, saving, and/or retrieving coefficients for the rainfall IDF curves for 2-yr, 10-yr, and 100-yr storms. The second step is entering the physical parameters of the basin (drainage length and height, runoff coefficient, area, and roof-to-ground time). The final step is choosing between the Kirpich and FAA equations for time of concentration, then solving for the time of concentration, rainfall intensity, and peak flow. I have ported this to the HP-48G+ and to Excel.

VINT: This program does what I call "vector interpolation." It is used to do linear interpolation between two rows or columns of data from a table based on known index values for the two rows/columns and for the desired interpolated values. It makes extensive use of the HP-42S's matrix capabilities.

NGAS: this program solves for the pressure loss in a natural gas pipe using the isothermal-compressible flow equation.

I also have the following SOLVER routines on my HP-42S:

TVM: Solves the Time Value of Money equation…just like we've always done it.

TB: Solves the equation for sizing thrust and anchor blocks for pressure pipelines.

PM$: Solves a simple project management calculation on project budgets/expenses that I had to do at my previous employer's.

HP: Solves the pump horsepower equation (HP = (Q*H)/(3960*e).

CW: Solves the Colebrook-White equation (i.e. solves the Moody Diagram).

HYT: Solves the equation for sizing hydropneumatic tanks.

FRC: Solves the equation for the frustum of a right cone/pyramid. This is useful for quickly checking the volume of a storm drainage pond.

LOGI: Solves logarithmic interpolation on a graph. Measure the distance between decades on a logarithmic axis using an engineer's scale, then measure the distance from the bottom of the decade to the point in questions, then use this data in the SOLVER routine. I use this mostly to determine coefficients for rainfall IDF curve from their log-log graphs.

TEMP: Converts Celsius to/from Fahrenheit.

FHYD: I can't remember what this is for and my notes are at the office. :-) I'm not recognizing the equation.

FHT: This solves the NFPA (?) equation for fire hydrant flow testing.

I have some less frequently used programs and solver routines that I input temporarily and delete when done due to lack of memory.

I have a feet-inches-fractions calculator that I wrote for the HP-41CX (see the MOHPC program library). Both the promised rewrite and the HP-42S version are about 90% done, but I keep finding more important things to do. I have also ported this to Excel.

So, YES, I still use a programmable calculator.

Edited: 18 June 2013, 1:17 a.m.


I use my HP-15C for handy portable calculations, usually sample size estimates, confidence intervals, HMS duration calculations, etc.

Generally, I find it easier to prototype any substantive program using R, including a couple of test cases, and then implementing an RPN version. Once I get the latter working I write out the HP-15C solution and test cases as the Limited Edition re-released calculator is prone to the power-loss bug every 2 or 3 months.

One recent example was an implementation of likelihood intervals for the binomial distribution using the built in solver, which meant I could get exact limits around the proportion estimate rather than simply +or- 2*se which is great for skewed likelihood functions such as when the proportion approaches 0 or 1.


Edited: 18 June 2013, 2:12 a.m.


Yes (32SII), they are very useful in calculating verious aspects of AHUs and the condition of air (others use dedicated slide rules, hx-diagrams and excel sheets). A colleague uses a program I wrote for the 50g to calculate the design of heat exchangers (optimizing number of circuits, rows and layers of pipes to have feed and return on one side - no design software from any DX manufacturer does this thus far AFAIK!

As soon as I have enough time to get into the 42S, I'll redo all programs for Free42 to get this on everyones desk and phone.


Not me but I remember Rainer Meng who demonstrated his theodolite at the Allschwil Meeting 2008:


He still uses this equipment in his work as surveyor



Edited: 18 June 2013, 6:08 a.m.


I use programmable calculators a lot, but usually for quick throw-away programs that solve an immediate problem. I leave the programs in memory for quite a while in case I need them again, but I rarely ever do.

For a lot of those, equation entry like the 17B and such might actually save me time, but I couldn't rely on it exclusively because sometimes I need algorithms that are difficult to express that way. (People have done some amazing things using the P() and G() functions, but I don't have time to figure out how to do those things.)


using the P() and G() functions

I think you mean L() and G(). Ah, but that's the challenge; how to write a program on a non-programmable calculator, or, can an equation be a program? The answer is "yes".


I am a professional EE and have a 28C at the office. I use it very often for simple calculations, which not really require a programmable machine, and until about 5 years or so, on my last position, also regularly with simple programs requiring complex math (dual frequency eddy current signal combination, for those who care). I wrote far more sophisticated programs in RPL (!) while I was a student, but I must admit I am no longer proficient in RPL.


I have routines programmed into my 35S and 50g that I use regularly for work. Radio line of sight, VSWR, power loss, and crystal frequency oscillator calculation for our microwave transmitter sites. Very helpful for me when I'm out on the road, especially at remote sites where there's little space to even set a laptop computer down and use it (a corner of a workbench, if I'm lucky). Much faster than using the laptop too. Works great for me. Good calculators need to stick around if I'm going to continue to be efficient. And, no, the smartphone apps just don't work that well for my situation, as slick and beautiful as the authors have made them.


I worked in applications engineering at a VHF/UHF power-transistor manufacturer in the mid-1980's and probably had all the same kinds of programmable-calculator programs as you. Back then it was on magnetic cards on a TI-59 though, which I loaded it at the beginning of each day. Many of the engineers in the engineering lab had their own HP-41's and I "joined the club" soon after. I agree with your smartphone comment.

Edited: 18 June 2013, 4:10 p.m.


As an EE I still use my HP-48SX quite a bit (weekly) at work. Mostly for quick or exploratory calculations but I have a fair number of conversion "programs" that I use on a semi-regular basis. When I am in the middle of a new circuit board design, the usage can go way up.

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