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

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37
votes
4answers
3k views

Are Mathematica 9 and 10 units really slow?

This generates 75 unitized pairs for a plot that displays physical units: ...
29
votes
7answers
3k 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: ...
29
votes
2answers
1k 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 ...
27
votes
2answers
573 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 ...
18
votes
3answers
682 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 ...
15
votes
2answers
688 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
1answer
2k 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, ...
14
votes
1answer
453 views

Unexpected behavior of UnitConvert

When I evaluate this expression: ...
13
votes
2answers
2k 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 ...
13
votes
5answers
1k 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 ...
13
votes
1answer
281 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: ...
12
votes
1answer
468 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
200 views

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

AstronomicalData objects are consistently in SI units: ...
11
votes
1answer
177 views

Why is this evaluation halved when adding units?

Why does this strange behavior occur when dealing with units and quantities? ...
9
votes
1answer
265 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 ...
8
votes
1answer
336 views

Cannot plot Quantity values with DateListPlot

Is there a way to use DateListPlot with Quantity values? I retrieved the following time series data from WolframAlpha: ...
7
votes
2answers
348 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
4answers
656 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 ...
7
votes
1answer
73 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, ...
7
votes
2answers
110 views

How to prevent $\text{Quantity}$ 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 ...
7
votes
0answers
386 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
3answers
310 views
6
votes
2answers
224 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 ...
6
votes
3answers
149 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
3answers
266 views

Can't force UnitConvert to be evaluated in Plot

I'm trying to use new units support in Mathematica 9. When I Plot Quantity functions everything is OK. ...
6
votes
1answer
98 views

DateListPlot failing on Inflation Adjusted TimeSeries

Ran across this (possible bug) today. Here's historical West Texas Intermediate oil prices: ...
6
votes
1answer
205 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? ...
6
votes
0answers
77 views

Spectral Radiance unit Flicks is not correct

I was pleasantly supersized that Mathematica (10.3, 10.4 and 10.4.1) had the unit $\text{flick}$ until I spent several hours trying to figure out why all my calculations were million times off! I ...
6
votes
0answers
364 views

Units: Custom-defined units possible?

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\; ...
5
votes
3answers
238 views

Is there a build-in function converting a quantity to one with mixed units (such as feet and inches)?

For example, I want to convert 179 centimeters into 5 feet and 10.4724 inches instead of 70.4724 inches (as this website did). Maybe in the future I would need to convert days to {years, months, days} ...
5
votes
1answer
361 views

Getting all physical units with prefixes

How we can get the list with all physical units and prefixes from WolframAlpha and make symbols from the result to be equal their corresponding quantities like described in this post?
5
votes
1answer
77 views

How do I perform exact unit conversions with irrational conversion factors?

Suppose I want to express $3h$ in units of $\hbar$ (where $h$ and $\hbar$ are the Planck constant and reduced Planck constant, respectively). By definition, $h = 2\pi\hbar$, but when I attempt this ...
5
votes
1answer
80 views

Plotting with units — getting the right axes labels

I have a simple example: Plot[UnitConvert[Quantity[x, "DegreesCelsius"], "DegreesFahrenheit"], {x, -25, 300}, AxesLabel -> Automatic] The x-axis has the ...
5
votes
1answer
117 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. ...
5
votes
1answer
283 views

UnitConvert works despite wrong dimension - bug or feature?

I am surprised that there are some cases where unit conversion works, even if the input- and output dimensions are clearly different: ...
5
votes
1answer
807 views

Simplifying to different units

Is there a way to force Mathematica to UnitSimplify to a different unit? For example, I would like kg m^2/s^2 to simplify to ...
5
votes
1answer
146 views

Dimensionless quantities

I must admit that I don't think this problem is really new. However, I haven't found a post dealing exactly with this aspect of the issue. I am doing calculation using Quantities, but I have problems ...
5
votes
2answers
141 views

Can I convert a list of units to a different base set?

I have a list of quantities with varying units (a short example list is shown below): ...
5
votes
0answers
54 views

Calculations with “Quantities” Run Slow. What am I doing wrong?

This code plots a 1000 point black body radiation curve in 0.7 seconds. ...
5
votes
0answers
197 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 ...
4
votes
2answers
127 views

What's wrong in “Watt”/(“Centimeters”)^2 [closed]

Why Mathematica returns the following input unevaluated? ...
4
votes
2answers
80 views

How to override DisplayForm of (mixed) time Quantity

What's the best approach to overriding DisplayForm for specific types of Quantity eg time especially w/ mixed units? Current is ...
4
votes
2answers
187 views

Draw and Quantity

I'd like to use Quantity in my graphics, but I can't figure out how to do it even for a very simple Circle. ...
4
votes
1answer
145 views

Calculating consumed internet data from bitmap of chart

My internet connection has a speed drawn up by the y axes has a scale as KB per second. and the x axes is time elapsed. if the x axes be from 0 to 40 minutes how can I calculate total consumed ...
4
votes
1answer
168 views

LowpassFilter in v10: unit issues?

Bug introduced in 10.0.0 and fixed in 10.1.0 I tried this with a clean start and no documents loaded. Now, evaluating the following on the documentation page for ...
4
votes
2answers
466 views

Why doesn't Mathematica divide out the Kelvins?

I thought I understood Mathematica V9 units. However, I can't get these numbers to plot, or even to come out to a nice clean unit of mass (say grams). The Kelvin's ...
4
votes
2answers
481 views

Using units and piecewise functions in Integrate

For simple cases, Quantities appear to be handled well by Integrate: ...
4
votes
1answer
166 views

NumberForm and units

NumberForm can be used to print Quantities to a specified precision. For example, x=Quantity[5.123456789,"Meters"]; 5.12346 m Print[NumberForm[x,{4,2}]] 5.12 m ...
4
votes
1answer
525 views

Problem in units convertion when multipliying Boltzmann constant and a temperature

When define the temperature of a variable in Celsius, Mathematica 9.0 does not calculate the right answer when multiplying by boltzmann constant. Example: ...
4
votes
0answers
70 views

Inequality involving Quantity stays unevaluated

Bug introduced in V10.1 and presisting through V10.4 An expression like this one a < x < b is represented as ...