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Questions tagged [units]

Questions about using, converting, or interpreting units of measurement in Mathematica.

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39
votes
4answers
3k views

Are Mathematica 9 and 10 units really slow?

This generates 75 unitized pairs for a plot that displays physical units: ...
37
votes
8answers
4k views

Simpler input for the new unit support

I've been playing with the new unit support in Mathematica 9. It seems very useful, but the syntax is very verbose. Instead of typing: ...
34
votes
2answers
2k views

Built-in unit strings recognized by Quantity?

It’s great that Quantity can utilize Wolfram Alpha to interpret unit strings that it doesn’t recognize, but I need my code to work on machines that do not have ...
31
votes
2answers
4k views

Unit Discovery: Is this some sort of a sick joke?

Alright, let's have some fun here. I am essentially following the documentation by Wolfram, just looking at different quantities. ...
30
votes
2answers
720 views

Speed of curated data calls in Version 10

Curated datasets underwent a significant overhaul in version 10, primarily in the way content is delivered in the form of Objects and Entities. Additionally, it appears that this change in content ...
29
votes
2answers
647 views

Should 0 * 5ft be 0 or 0ft?

After playing with the new quantity system in Mathematica 9 for a while, I keep stumbling over this issue: 0 * Quantity[1, "Meters"] is not the same as ...
20
votes
1answer
4k views

Is there a “No Units” (i.e., dimensionless) unit?

I would like to be able to call the Quantity function with a null unit so that it returns the original dimensionless value. For example, ...
19
votes
3answers
1k views

Kelvin per Kelvin Difference

Bug introduced in 9 and partially persists through 10.2 or later The specific bug described in the original question is fixed ("Kelvin" is correctly recognized as <...
17
votes
5answers
2k views

Implementing CGS unit system in Mathematica 9

So I've just installed the trial version of Mathematica 9. The first noticeable feature for me is the new built-in physical units. I used AutomaticUnits package ...
16
votes
3answers
921 views

How to convert between various ItemSize/ImageSize units?

How can one convert between the implicit units used by Grid (ems and line height for horizontal and vertical dimensions) and printers points (in ...
15
votes
2answers
1k views

Where to see all Mathematica units [duplicate]

Is there a tutorial page that have all Mathematica units? I sometimes have hard time figuring out the correct unit spelling when using quantities
15
votes
2answers
6k views

Numerical value of physical constants Mathematica 10

Is there a way to use the physical constants in calculations and have Mathematica 10 figure out the final unit and numerical magnitude? When I try ...
15
votes
1answer
579 views

Unexpected behavior of UnitConvert

When I evaluate this expression: ...
14
votes
4answers
4k views

How to dequantify units in mathematica?

Is there a function which applied to a quantity returns its numerical value so I for instance can fill it into my Predictorfunction?
14
votes
4answers
1k views

Automatically add appropriate prefix to Quantity

Is there a function that automatically adds the appropriate prefix to a Quantity object? For example, I would like a function ...
14
votes
1answer
606 views

Why is this evaluation halved when adding units?

Bug introduced in 9.0 or earlier and persisting through 11.2 or later Why does this strange behavior occur when dealing with units and quantities? ...
13
votes
1answer
326 views

Possible bug: Quantity[2,“meters”] returns 2 None meters

Bug introduced in version 10 or earlier and fixed in version 10.0.2 I'm using 10.0 for Linux. Trial 1: Quantity[2,"meters"] 2 None meters Trial 2: ...
13
votes
1answer
295 views

Is Quantity necessary?

Soft question: are Quantity - and newly added MixedUnit and MixedMagnitude - needed in a ...
12
votes
1answer
520 views

How do I seamlessly migrate from the older Units package to Mathematica 9's Quantity objects?

I have several notebooks that make use of the Units package and would like to be able to work simultaneously with the older units and ...
11
votes
1answer
241 views

How can I get curated data to be expressed consistently in SI units?

AstronomicalData objects are consistently in SI units: ...
11
votes
4answers
304 views

How to prevent Quantity calculations from converting units

I have an accrual calculation that I would like to preserve the units even though they are of the same dimension (e.g. time). For example, I would like the following ...
11
votes
1answer
131 views

Display bug in Dataset's UnitConvert handling

Bug introduced in 11.0.1 or earlier and fixed in 11.1.0 Is this yet another annoying regression in v11 Dataset type handling? The display form seems to be a ...
10
votes
1answer
307 views

Where is the unit after a calculation?

I was playing with some of the new features, and when I type e.g. Quantity[10, "ml"] + Quantity[250 - 100, "ml"] I get ...
10
votes
2answers
394 views

Is it reasonable to have both TemperatureUnit and TemperatureDifferenceUnit?

When adding the bugs header to the question "Kelvin per Kelvin Difference" I was confused by the fact that I cannot determine for sure whether the described bug is fixed in version 10.2 or not: from ...
10
votes
1answer
666 views

Mathematica seems confused about Kilograms vs KilogramsForce

This does what I expect: Quantity["Kilograms"*"Meters"] // InputForm Quantity[1, "Kilograms"*"Meters"] This, on the other hand, bungles the units: ...
9
votes
1answer
116 views

Why does the front-end no longer like MixedRadix as an argument for UnitConvert?

I often find MixedRadix very useful for make certain kinds of unit conversions. For example, ...
9
votes
2answers
78 views

Can Quantity interpretation be accepted using the keyboard?

Entering Ctrl+= on selected text results in the display of an interpreted Quantity, with the option to accept it, or choose other interpretations. The only way I ...
9
votes
2answers
185 views

Why does using different units but same physical value give different result?

I'm trying to define a variable with the value of the thermal constant $V_T$. The value of the thermal constant is given in Volts as $V_T = \frac{k T}{q}$, where $k$ is the Boltzmann constant and $q$ ...
8
votes
3answers
1k views

Why are Dalton and Grams / Moles not equivalent units?

The following code throws an error: UnitConvert[Quantity["Daltons"], "Grams"/"Moles"] Why?
8
votes
1answer
673 views

Using physical dimensions in Mathematica DSolve

I would like to calculate a system of two differential equations in Mathematica using DSolve, like: ...
8
votes
2answers
676 views

Physical (and other) constants

As Mathematica documentation likes to say, "As of Version 9.0, physical constant functionality is built into the Wolfram Language". After clicking on the ">>", one ...
8
votes
1answer
307 views

Change units in PlanetData[“Earth”, “Diameter”] from miles to km

When I enter AstronomicalData["Earth", "Radius"] I get Quantity[6.3674447*10^6, "Meters"] I would have preferred kilometers, ...
8
votes
1answer
219 views

Working with degrees minutes and seconds without conversion

Is there a way to work with angles in DMS without converting them to decimal degrees, that is to sum them, subtract them? I do not know how to even enter it without using string. My idea is something ...
8
votes
4answers
826 views

Suppress connection to Wolfram|Alpha when making unit conversions

I want to speed up calculations with unit conversions. I suspect primarily that some units evaluate from Wolfram|Alpha. Any way to prevent this automatically, so that Mathematica throws errors/...
8
votes
1answer
379 views

Cannot plot Quantity values with DateListPlot

Bug introduced in 9.0.0 and fixed in 9.0.1 Quantity is new in 9.0.0 Is there a way to use DateListPlot with ...
8
votes
0answers
556 views

Units: Custom-defined units possible? [closed]

Converting between revolutions per minute (RPM) and revolutions per second (RPS) is not straightforward for me in Mathematica. I know that $1\; \text{RPM} = \frac{2\; \times\; \Pi\; \text{Radian}}{\...
7
votes
4answers
407 views

Mathematica function which formats Physics calculation

One small step toward automating homework :) My lecturer doesn't accept calculations done in Mathematica code as homework. I have 30 pages of small calculations such as the one below. I don't want to ...
7
votes
2answers
469 views

Convert units to String

Is there a way to convert compound units to string? For example, I have "Newtons"/"Meters"^2, how to I convert it to "N/m^2"? I know If I do the following ...
7
votes
2answers
805 views

Why do I get QuantityUnits`Private`ToQuantity when trying to use units?

I'm unable to use units in mathematica (10.3.1) When I do Quantity[500, "Feet"] + Quantity[50, "Meters"] the answer I get is ...
7
votes
1answer
436 views

Moles/Liters doesn't get simplified to Molar even though Molar*Liters gets simplified to Moles

Why can't Mathematica 9 simplify mol/L to M, when it can simplify M*L to mol? ...
7
votes
1answer
180 views

DateListPlot failing on Inflation Adjusted TimeSeries

Bug introduced in 10.0 or earlier and solved in 10.4 Bug introduced in 10.0 or earlier and persisting through 11.0.1 or later First bug. See output of ...
7
votes
1answer
293 views

Quantity and Trig functions

I have a bunch of data to which I've assigned units using Quantity, including some angular measurements in degrees. I'd like to be able to use these measurements ...
7
votes
0answers
184 views

Spectral Radiance unit Flicks is not correct

Bug introduced in version 10.3 or earlier and fixed in 11.1. I was pleasantly surprised that Mathematica (10.3, 10.4, 10.4.1, 11.0 and 11.0.1) had the unit $\text{flick}$ until I spent several hours ...
7
votes
0answers
441 views

Incomplete implementation of units?

I've been playing around with the new units capability in MMA9 and I'm becoming a bit frustrated with what I perceive as an incomplete implementation of this capability and I'm wondering if there are ...
6
votes
2answers
1k views

How to get Planck length in meters to 6 decimal places

I want Mathematica to format quantities to more decimal places than the default. For example I have tried ...
6
votes
2answers
1k views

Conversion between GB and MB (and KB)

UnitConvert[Quantity[1, "GB"], "MB"] Quantity[1000, "Megabytes"] Which is NOT something we would normally expect. Is this a bug? How can I use 1024MB =...
6
votes
3answers
425 views

Why does this Quantity calculation lose precision?

...
6
votes
1answer
200 views

How to create fast functions based on units?

Using units is a good means for rapidly developing code, since it provides some error control. Hovewer, using Mathamatica functions containing units appears to be copmutationally inefficient. ...
6
votes
3answers
178 views

Why does adding 6.1 seconds display as having added 6.099?

Why does adding 6.1000000 seconds to a DateObject display as having added 6.099? If I copy the Out[20] element from this picture, it contains the correct value: ...
6
votes
2answers
595 views

Using units and piecewise functions in Integrate

For simple cases, Quantities appear to be handled well by Integrate: ...