Kahan on HP calculators: Solve, Integrate and Matrix Operations

William Kahan, winner of the Association for Computing Machinery's A.M. Turing Award, describes his work as a consultant to HP on its celebrated line of programmable calculators, particularly his work to squeeze highly efficient solve, integrate, and matrix functions into their severely limited hardware capabilities. This clip is taken from an interview conducted with Kahan by Thomas Haigh for the ACM on 12 March, 2016 in Berkeley, California. Video of the full interview is available as part of Kahan’s ACM profile at amturing.acm.o....

[@billhatzistavros4824]

Recalling the days I walked into my University bookshop and excitedly handed over my money to pick up a HP 33c then a couple of years later to pick up a HP 15c, were some of the most etched memories in my life!

[@Cynthia_Cantrell]

I got my first HP calculator in 1985 (a 41-CV with Advantage Pack) after my TI calculator died in the middle of a chemistry mid-term. I still have it, along with at least 3 other HPs. I can no longer use calculator with an equals key. I'm an EE myself, so I can appreciate all the great work guys like William did. I look up to them!

[@frankwc0o]

Goes back to those who use the product and those who don't. Those who use calculators understand what is needed.

[@whippoorwill1124]

The 41-CV was what the rich kids flourished when I started university - only two in my year had them. Over 40 years later, still nothing can touch those HP calculators: I use my 48GX every day, and run Droid48 on my phone and Emu48 on all my computers.

[@skysurfer5cva]

I bought an HP-34C in September 1979 at the start of my senior year of college, specifically because of the SOLVE and INTEGRATE functions…and because I couldn't afford the HP-41C, which released at the same time. I found both functions to be very helpful in finishing my civil engineering degree. I remember solving an iteration problem on a final exam that semester by recording a program in the HP-34C, writing the re-arranged equation and program steps on my test paper along with my initial guesses and a brief explanation of the SOLVE function, then reporting the result. By hand, this problem would have taken perhaps 20 minutes, but my method took only about 2 minutes. My professor loved my approach, and because he used an HP-45 he understood my program. I also appreciated the extra chapter in the manual. As a not-yet-professional, I needed the extra guidance. THANK YOU, Professor Kahan.

[@BoydWaters]

Oh yes Professor Kahan was perhaps the leading contributor to the IEEE Floating Point standards, then the design of the Intel 8087... He taught Numerical Computing at UC Berkeley for a very long while.

[@dosgos]

So much joy every time I pull out an HP calculator; even the newest iterations of iPhones didn't come close. I love the logic and build quality behind HPs calculators. So nice to see the man behind the development.

[@rhymereason3449]

As a young engineering student my first HP was an HP25 - I loved programming that machine and it induced me to change my major to computer programming. My second HP was the 15c preciously for the solve and integrate functions. Over the years I have owned the 25, 10c, 11c, 12c, 15c, 16c, 17b, 19c, 28, 41cv, 41cx, 32, 48sx, 50g. Thank you for the wonderful products you helped create that have given me many years of joy and utility.

[@robertland2616]

I share you “pain”. I bought 3 HP-50g when I heard they were discontinued!

[@qrplife]

Thank you for the 15C - it’s an amazing device that I still use to this day. Fun fact: I recently found a 12C in perfect condition, in the box, with all the documentation at a flea market in the desert, paid a total of $1 for it. Score!

[@Quidisi]

Wow! What a find!!!

[@deltawing9]

Thank you for your amazing contributions! My first HP calculator was the HP-45, pretty early model, followed by several work calculators. They were and still are a reliable point in life.

[@EdwinSteiner]

I'm watching this with my cherished original HP-15C in hand. Both the calculator and its manual are works of art. Prof. Kahan did an amazing and lasting job.

[@odarge]

He is thus the guy behind the 15C, waw, amazing!, So much good memories with it !!! do they realise how their fantastic tools have change people minds? 👍👍

[@ALaModePi]

I've had an HP-55, HP-67, and HP-41c. I've got an emulator for the 48/49 series as well as the Prime on my phone now. The one thing I miss is the tactile feeling of the solid click of the HP keyboards. It's probably because I started working with computers very early on that RPN appealed to me so much. I've always been able to think in better in those terms than relying on how the calculator is programmed to interpret algebraic notation. It's great hearing the thoughts of the people involved in creating and programming of these calculators.

[@zerobeat2020]

Used to have an 11C when I studied engineering in the 80s, but now I have a 15C and I love it!

[@lemd49]

Got my first HP calculator in 1975, an HP25 (Second year electrical engineering) and still use it today, although modified the battery to NiMH. Then got an HP15C and a HP19B financial calculator, still all working. Great machines.

[@Chris-hf2sl]

I have both a 28C and a 28S calculator and despite their age, they are far superior to anything I've seen since. The only negative is the poor screen, which is sometimes difficult to read. Once you get used to PRN it's so easy and reliable - no more guesswork as to whether to enter √2 or 2√ like on other calculators.

[@stevew3978]

My first HP calculator was the HP41C. It cost me more than $400 in 1981, but it was worth every penny. In 2024 dollars, it would be equivalent to around $1,500 today.

[@hansdevreught5459]

In august 2023 the HP15C collector's edition will be relaesed. Price is quite affordable.

[@JimmyArogen]

At work we had a diskussion about the HP calculators of old, and the manuals came up. 30-50 years on and people still talk about the quality of the manuals. -Excellence is forever and no one cares for the profit hungry

[@ericfielding668]

What a wonderful story. CPA with a math degree here. Thanks for the complex numbers and matrices. I've got a few HPs. The 48G is my daily driver; it still has great buttons. My phone has Free42 on it (I'll probably get a Swiss Micros unit with buttons at some point). Every year I program up the latest payroll source deductions formulae on my calculators.

[@MrWaalkman]

Still have and use a 15C. What a great calculator!

[@markstroemberg]

The 15c really is my favorite as well!

[@MrSchattka]

Still have mine and still use it.

[@diversionmary]

That was really interesting. Thanks algorithm!

[@carloscm1323]

The amazing moment is...7:17

[@dopplerdog6817]

KAHANNN! Thanks for that glorious 15c I loved so much, it was brilliant! But why are you wearing two buttoned shirts at the same time?

[@hectorpelaez4992]

Para Mí la mejor Calculadora hp15c la función Solve poderosa operación con matriz y programable. para la universidad en México economía 1987. gracias a este genio, los manuales una delicia aprendías en ellos matemáticas y programación tuve la 11c 15c y 28c 28s

[@jcamargo2005]

I never needed to own one, using early PC software instead, but for sure it was a top quality product

[@kimchee94112]

HP 15C, 30 years later still on the same batteries.

[@jeanpierrecassou5003]

Nul. C'est du podcast, pas de la vidéo