Maths tools - from slide rule to software, the engineer's friends

When I started my career in a drawing office in the early 70’s, like most engineers I found myself needing to carry out mathematical calculations. These were to start with, such things as working out the size of hydraulic pump I would need to order, what size of storage tank for the hydraulic fluid or the size of accumulator to provide shock absorption within a hydraulic system. Later on, in my career I needed to know the total rainfall and peak flow for a specific catchment area and storm duration.

To start with these calculations were mainly carried out using basic arithmetic, pencil, paper and an eraser. The only aids I had was slide rule, log tables or the shared office printing calculator. While I did have a set of log tables and occasionally used them, the slide rule was my best friend, as I could multiply, divide, obtain the squares or square roots.

a typical slide rule as used in design offices
Example of a slide rule

The office printing calculator was like many early pocket calculators. It had buttons to allow adding, subtracting, multiplying and dividing. Unlike a pocket calculator it sat on a small trolley table so that it could be moved around the drawing office. The main advantage over the slide rule was it had a paper role that allowed the calculations to be printed out for later reference.

plastic slide rules for calculating hydraulic formulae
Mannesman Rexroth hydraulic slide rules

At the same period companies such as Sinclair and Hewlett Packard started to produce the first pocket calculators. These didn’t have many of the features of later models, but they were easier to use than the slide rule and more convenient than the office printing calculator. Paper and pencil still remained the only option to record the results. Pocket calculators gradually became more sophisticated during the 70’s with memories that could store and retrieve data and some models used such low amounts of energy that they could use solar cells. Programmable versions were introduced by the end of the decade. Like most engineers during the 70’s I replaced my slide rule with the latest pocket calculator.

a texas instruments ti - 57 ii programmable calculator
Texas Instruments TI-57 II programmable calculator

During the 80’s the drawing office gradually changed from drawing boards with drafting machines to desktop computers. My first office computer was an IBM AT machine. It had dual screens, a digitiser tablet and Autodesk’s computer-aided design (CAD) software, AutoCAD release 9.0 installed. The AT machine unlike the IBM XT had a math co-processor installed. This was needed to run AutoCAD, the second colour screen, the main screen was black & white, and digitiser were also added to the basic machine to allow AutoCAD to be used.

As far as I can remember I didn’t have any other software installed. Reports, orders and other documents were still being typed using conventional typewriters by secretaries. The secretaries in the office were eventually given desktop computers with WordPefect 5.1 installed to replace their typewriters. Everything was still printed at this stage. The company also decided to install Lotus 1-2-3 on one of these machines. Lotus 1-2-3 was intended to be an office suite of applications. The 1-2-3 stood for word processor, spreadsheet and database. The software was however used as a database rather than a spreadsheet. It didn’t take long for the software such as 1-2-3 to migrate unofficially to other machines in the office. Once I discovered it could be used as a spreadsheet, thanks in part to a suggestion from my wife, I never looked back. Within a short time, Lotus 1-2-3 had supplanted my pocket calculator.

image of five 3 1/2 floppy discs containing mathcad 5.0 installation files
Five 3 1/2" floppy discs containing Mathcad 5.0 installation files

At the same time, I was also investigating other software that I could use to make my job easier. I came across a fairly cheap piece of software that had interesting possibilities. It was Mathsoft’s Mathcad version 2.5. It run on the

Microsoft disk operating system (MS DOS) but had a reasonable visual interface for a DOS programme. It seemed like the perfect piece of software for an engineer. I could use it just like a piece of paper and write out any equations just as I would on paper. The real benefit was that not only could it do what a pocket calculator could do, it also included support for units. This had advantages over everything I had used previously. I could input a mix of imperial units and the SI units into my calculation and know that I had the correct answer in the correct units. No more risk of decimal points in the wrong place or having to convert manufacturers imperial information into metric before I started. Remember, although the metric system was adopted in 1965, many older engineers still used the older imperial units. The United States (US) was still using imperial units so components purchased from the States were in imperial units or United States customary units (USC).

During my career I have continued to carry out all my calculations either using various spreadsheet applications or Mathcad. The introduction of Microsoft Windows 3.0 in 1990 saw the slow replacement of MS DOS across industry and the rise of several different business office software packages. In 1990 Microsoft released the first version of Office consisting of Word, Excel and PowerPoint. By 1993 Borland had a competing office package consisting of WordPerfect, Quatro Pro and Paradox.

I had already been using WordPerfect and had a growing dislike for Microsoft products, so when I was asked to select a suitable Windows office package for the company, I selected Borland Office. This included Quatro Pro spreadsheet which I used along with the Windows version of Mathcad. Due to a change of management and their wish to standardise software across the group, Microsoft Office was adopted to replace Borland Office. Since Microsoft Excel had similar functions to Quatro Pro this was not really a problem, but I did have to replace my spreadsheet templates to use them with Excel.  By the late 90’s Microsoft was the dominant Office software and other companies I worked for also used the Microsoft product. The new millennium saw me working for a different company, but they also used MS Office, so Microsoft Excel and Mathcad were my two main pieces of software to use for all my engineering calculations.

Historical Mathcad 15.0 screenshot

Screen shot of Mathcad 15.0

In 2006, Parametric Technology Corporation (PLC) purchased Mathcad and made changes to the support policy that meant in order to get updates a maintenance licence was required. The first year I purchased the licence, which cost the same as I had spent in previous years on Mathcad upgrades. Since as you will see above, I really didn’t need support for Mathcad 15.0 after all the years I had been using it. The new annual maintenance licence did come with their new version of Mathcad Prime 1.0. I did try it, but it was really not developed to a state that it was practical to use. I decided the following year I would stick with the Mathcad 15.0 and save myself the cost of the annual licence for software I wasn’t going to use and didn’t like.

Everything was fine until disaster occurred 2016, when my computer died. I was self employed by this time. I purchased a new state of the art laptop and I installed all my software on the new machine. All that is except Mathcad 15.0, which I had purchased a licence to use before PTC took over the company. I contacted local distributer and was told if I wanted to use Mathcad 15 in the future, I would have to purchase all the maintenance licences since 2012. This was dearer than purchasing a completely new licence. If I did that, I would get a copy of Mathcad 15 free along with Mathcad Prime 3.1. After telling the agent I wasn’t interested, I now had to fine an alternative maths software package to replace Mathcad.

My search was on, but in the meantime, I worked with Microsoft Excel to produce templates with the Equation editor to show how the calculations were carried out. I even managed to write functions to allow me to enter values with different units so I could change the answers to reflect the units selected.

The hunt for an alternative resulted in downloading and trying various software applications, but while they could do the basic calculations, even statistics and calculus, they did not have built in units. I was just about to give up when I downloaded a copy of SMath Desktop. This did everything that Mathcad did, it even allowed me to load my old Mathcad 15.0 files. The best part about SMath was that it is free. The developer only askes for a donation to the SMath project.

smath desktop version 0.99 (build 6884) screenshot
Screen shot of SMath Desktop 0.99 (build: 6884)

Unfortunately, retirement came along before I could make use of the benefits of this software for my business. However, I have this website linked to calculation sheets on SMath Cloud and am enjoying my retirement using the software just for fun.

This is a tiny, powerful, free mathematical program with WYSIWYG editor and complete units of measurements support. It provides numerous computing features and rich user interface translated into about 40 different languages. Application also contains integrated mathematical reference book”.

While I agree with the above statement in full, I have to confess I pinched it directly from the SMath Studio website. Anyone involved in engineering or science disciplines or students at college that need good reliable mathematical calculation software, I can recommend SMath Studio.

I have SMath in the Cloud live calculation sheets linked to this website. To see how SMath works view my Calculation Sheets page on this website. 





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Web page last updated  27 January 2019

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