Quantities and additional dimensions

[ValeryOchkov]

It will be very dood work not only units but with quantities too.

For example I have in this calculation mass of water/steam and mass of gas.

This quantities have same unit of mass but in is two different quantities:

[PhilipOakley]

Valery Ochkov wrote:

It will be very dood work not only units but with quantities too.

For example I have in this calculation mass of water/steam and mass of gas.

This quantities have same unit of mass but in is two different quantities:

I agree. The method for achieving that I would propose is to provide additional user "Dimensions" (Dimensions being indicators of thing we believe are independent, as per the example).

Thus we would have a set of spare user dimensions U [0;9], along with the angle dimension I have already proposed Beyond the Money Dimension - The inclusion of Angles as a unit. The "Uno" dimension and other distint quantity signifiers would be a worthwhile benefit for software support.

There is a good review article on the issues around getting the SI ready for the automation age that MathCAD has already pioneered (and needs to keep pioneering) at http://iopscience.iop.org/0026-1394/47/6/R01/ [stacks.iop.org/Met/47/R41]

There is another paper by Hall on the needs of software systems"Software Support for Physical Quantities" http://mst.irl.cri.nz/Portals/5/enzcon.pdf

MathCAD needs to be ahead of the game, not lagging.

Philip

[ValeryOchkov]

Now I do so:

kJ/kgws := 1000*J/kg

kJ/kggas := 1000*J/cd (Mathcad 11)

But must be so:

[RichardJ]

Thus we would have a set of spare user dimensions U [0;9]

Why limit it to 10? I can easily envision cases where somebody would want to track a lot more independent quantities than that.

[PhilipOakley]

Richard Jackson wrote:

Thus we would have a set of spare user dimensions U [0;9]

Why limit it to 10? I can easily envision cases where somebody would want to track a lot more independent quantities than that.

Because if you use Hexadecimal you get unit symbol confusion

How many is "a lot more"? We need real numbers, preferably integers, hopefully positive ones.

Philip

[RichardJ]

How many is "a lot more"? We need real numbers, preferably integers, hopefully positive ones.

Why put any arbitrary limit on it? Why do you need a number? If I want to create a worksheet that calculates the entire world's import and export flow of fruits and cheeses, perhaps I want to track every type of fruit and every type of cheese as separate quantities.

[Liv]

No limit, because a serious chem eng (like I try and tend to be) may face more practical use of units, like :

1) 1 { bottle Sauvignon } + 1 { bottle Merlot } + 1 { bottle Franc } = 3 { bottle Bordeaux } ;

2) 100 { ml dry Martini } + 2 { ice cubes } = 1 { Martini on the rocks } .

Just for fun (and apologize my “distraction” moment),

Best, Liv.

[jhardy1]

Let's not forget:

3 {bottle Bordeaux} / 3 {people} = 1 {dinner party}

but:

3 {bottle Bordeaux} / 1 {people} = 1 {giant hangover}

[StuartBruff]

jhardy1 wrote:

Let's not forget:

3 {bottle Bordeaux} / 3 {people} = 1 {dinner party}

but:

3 {bottle Bordeaux} / 1 {people} = 1 {giant hangover}

Ah! that's an idea - subjective units. The Scoville is another one where user-defined mappings can occur, eg, 1 MSHU can be represented as "ARRGGH! Pass the Fire Hydrant", "Mildly piquant" or "Sasquatch". However, I am somewhat surprised that somebody with the surname 'Hardy' would regard a mere 3 bottles of red as "Giant Hangover" rather than "Apéritif" 🙂

Back to standard units, I'd like to see the Potrzebie System implemented, can't let Google and that Wolfram chappie take the furshlugginer ground on this one!.

[Moreton]

Looks like they just did. Look at the "book" example on

http://blog.wolfram.com/2010/12/09/automatic-physical-units-in-mathematica/

[PhilipOakley]

Well MathCAD had all the info from May 2009 (see my docs file). Mathematica only had it for a few months following a discussion I had with Jon McLoone last summer. It just missed being an integral part of Mathematica 8.

It's only omission is that there is no option to require the Sine function (etc.) to demand Angle dimensioned inputs, nor and option to get the inverse functions to produce Angle dimensioned results. But beyond that Jon has done an excellent job.

I'm expecting (holds breath) it to show in V16 / Prime 2. ;-]

Philip

[StuartBruff]

Philip Oakley wrote:

Well MathCAD had all the info from May 2009 (see my docs file). Mathematica only had it for a few months following a discussion I had with Jon McLoone last summer. It just missed being an integral part of Mathematica 8.

I think there have been at least 2 major releases of Mathematica since I put my first proper Mathcad wish list together (including a working demo of a multi-dimensional array capability and backdoor programmable 3D graphics) ... I'd hate to guess how many since Valery started his MM proposal.

Stuart

[olivierlp]

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