Engineering notation: Difference between revisions

Revision as of 12:01, 26 April 2021

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Based on an idea by Peter D. Dickinson<ref name="Dickinson_1976"/><ref name="Gordon_1969"/> the first [[calculator]] to support engineering notation displaying the power-of-ten exponent values was the [[HP-25]] in 1975.<ref name="Neff_1975"/> It was implemented as a dedicated display mode in addition to scientific notation.

In 1975, [[Commodore Business Machines|Commodore]] introduced a number of scientific calculators (like the [[Commodore SR4148|SR4148]]/SR4148R<ref name="Commodore_SR4148R"/> and [[Commodore SR4190R|SR4190R]]<ref name="Commodore_SR4190R"/>) providing a ''variable scientific notation'', where pressing the {{button|EE↓}} and {{button|EE↑}} keys shifted the exponent and decimal point by ±1<ref group="nb" name="NB_Exp-Shift"/> in ''scientific''<!-- not engineering! --> notation. Between 1976 and 1980 the same ''exponent shift'' facility was also available on some [[Texas Instruments]] calculators of the pre-[[LCD]] era such as early [[TI SR-40|SR-40]],<ref name="SR-40"/><ref name="SR-40_Manual"/> [[TI-30]]<ref name="TI-30"/><ref name="TI-30_Manual"/><ref name="TI-30-BR"/><ref name="TI-30_BR_Manual"/><ref name="TI-30_2"/><ref name="TI-30_RCI"/><ref name="TI-30_1"/><ref name="TI-30_Super"/> and [[TI-45]]<ref name="TI-45"/><ref name="TI-45_Manual"/> model variants utilizing ({{button|INV}}){{button|EE↓}} instead. This can be seen as a precursor to a feature implemented on many [[Casio]] calculators since 1978/1979 (e.g. in the [[Casio FX-501P|FX-501P]]/[[Casio FX-502P|FX-502P]]), where number display in ''engineering'' notation is available on demand by the single press of a ({{button|INV}}){{button|ENG}} button (instead of having to activate a dedicated display mode as on most other calculators), and subsequent button presses would shift the exponent and decimal point of the number displayed by ±3<ref group="nb" name="NB_Exp-Shift"/> in order to easily let results match a desired prefix. Some graphical calculators (for example the [[Casio fx-9860G|fx-9860G]]) in the 2000s also support the display of some SI prefixes (f, p, n, μµ, m, k, M, G, T, P, E) as suffixes in engineering mode.

==Overview==

Compared to normalized scientific notation, one disadvantage of using SI prefixes and engineering notation is that [[significant figure]]s are not always readily apparent when the smallest significant digit or digits are 0. For example, 500&nbsp;μmµm and {{val|500e500E-6|u=m}} cannot express the [[uncertainty]] distinctions between {{val|5e5E-4|u=m}}, {{val|5.0e0E-4|u=m}}, and {{val|5.00e00E-4|u=m}}. This can be solved by changing the range of the coefficient in front of the power from the common 1–1000 to 0.001–1.0. In some cases this may be suitable; in others it may be impractical. In the previous example, 0.5&nbsp;mm, 0.50&nbsp;mm, or 0.500&nbsp;mm would have been used to show uncertainty and significant figures. It is also common to state the precision explicitly, such as "{{gaps|47&nbsp;kΩ|±|5%}}"

Another example: when the [[speed of light]] (exactly {{val|299792458|u=m/s}}<ref name="CUU_2014_c"/> by the definition of the meter and second) is expressed as {{val|3.00e800E8|u=m/s}} or {{val|3.00e500E5|u=km/s}} then it is clear that it is between {{val|299500|u=km/s}} and {{val|300500|u=km/s}}, but when using {{val|300e6300E6|u=m/s}}, or {{val|300e3300E3|u=km/s}}, {{val|300000|u=km/s}}, or the unusual but short {{val|300|u=Mm/s}}, this is not clear. A possibility is using {{val|0.300e9300E9|u=m/s}} or {{val|0.300|u=Gm/s}}.

On the other hand, engineering notation allows the numbers to explicitly match their corresponding SI prefixes, which facilitates reading and oral communication. For example, {{val|12.5e5E-9|u=m}} can be read as "twelve-point-five nanometers" (10⁻⁹ being ''nano'') and written as 12.5&nbsp;nm, while its scientific notation equivalent {{val|1.25e25E-8|u=m}} would likely be read out as "one-point-two-five times ten-to-the-negative-eight meters".

Engineering notation, like scientific notation generally, can use the [[E-notation]], such that {{val|3.0e0E-9}} can be written as 3.0E−9 or 3.0e−9. The E (or e) should not be confused with the [[E (mathematical constant)|exponential ''e'']] which holds a completely different significance. In the latter case, it would be shown that 3''eE''⁻⁹ ≈ {{val|0.00037023}}.

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== References ==

{{reflist|refs=

<ref name="Gordon_1969">{{cite journal |title=Introducing the Computing Counter - Here is the most significant advance in electronic counters in recent years |author-first1=Gary B. |author-last1=Gordon |author-first2=Gilbert A. |author-last2=Reeser |journal=[[Hewlett-Packard Journal]] |publisher=[[Hewlett-Packard Company]] |volume=20 |number=9 |date=May 1969 |pages=2–16 |url=http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1969-05.pdf |access-date=2017-06-04 |url-status=live |archive-url=https://web.archive.org/web/20170604195957/http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1969-05.pdf |archive-date=2017-06-04 |quote=[...…] Measurements are displayed around a stationary decimal point and the display tubes are grouped in threes to make the display more readable. The numerical display is accompanied by appropriate measurement units (hertz, second, etc.) and a prefix multiplier which is computed by the counter (e.g., k for kilo, M for mega, etc.). There are 12 digital display tubes, to permit shifting the displayed value (11 digits maximum) around the fixed decimal point. Insignificant digits and leading zeros are automatically blanked so only significant digits are displayed, or any number of digits from 3 to 11 can be selected manually. Internally, however, the computer always carries 11 digits. [...…]}} (NB. Introduces the HP 5360A Computing Counter.)</ref>

<ref name="Dickinson_1976">{{cite patent |inventor-last=Dickinson |inventor-first=Peter D. |pubdate=1976-10-19 |fdate=1975-05-19 |pridate=1975-05-19 |title=Calculator Apparatus for Displaying Data in Engineering Notation |assign1=[[Hewlett-Packard Company]] |country-code=US |patent-number=3987290 |url=https://www.google.ch/patents/US3987290}}. "[...…] A computing counter [...…] has been developed that displays data in engineering notation with the exponent expressed in alphabetic form rather than in numeric form, such as f in place of −15, p in place of −12, n in place of −9, μ in place of −6, m in place of −3, k in place of +3, M in place of +6, G in place of +9, and T in place of +12. This device, however, is limited to displaying only those numeric quantities for which there exists a commonly accepted alphabetic exponent notation. This device is also limited in the range of data that it can display because the size of the exponent display area is limited, and would be unduly large if required to contain all of the alphabetic characters necessary to represent every exponent that is a multiple of three, for example, in the range −99 to +99. [...…]" (US 05/578,775)</ref>

<ref name="Neff_1975">{{cite journal |title=Three New Pocket Calculators: Smaller, less Costly, More Powerful |author-first1=Randall B. |author-last1=Neff |author-first2=Lynn |author-last2=Tillman |journal=[[Hewlett-Packard Journal]] |publisher=[[Hewlett-Packard Company]] |volume=27 |number=3 |date=November 1975 |pages=1–7 |url=http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1975-11.pdf |access-date=2017-06-10 |url-status=live |archive-url=https://web.archive.org/web/20170610140406/http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1975-11.pdf |archive-date=2017-06-10}} [http://www.hpmuseum.org/journals/wooda.htm<!-- https://web.archive.org/web/20170610135819/http://www.hpmuseum.org/journals/wooda.htm -->]</ref>

<ref name="Commodore_SR4148R">http://www.wass.net/manuals/Commodore%20SR4148R.pdf</ref>