Questions about calculating with units in Mathematica.

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30
votes
4answers
2k views

Are Mathematica 9 units really slow?

This generates 75 unitized pairs for a plot that displays physical units: ...
26
votes
7answers
2k 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: ...
25
votes
2answers
529 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
2answers
625 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 Internet access. Is there a complete ...
14
votes
2answers
494 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
14
votes
1answer
372 views

Unexpected behavior of UnitConvert

When I evaluate this expression: ...
10
votes
1answer
372 views

Kelvin per Kelvin Difference

I'm trying to use Mathematica units more often, but I've run into the following problem: ...
10
votes
1answer
339 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 ...
10
votes
5answers
785 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 ...
9
votes
1answer
234 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 ...
9
votes
1answer
1k 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, ...
8
votes
2answers
434 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 ...
8
votes
1answer
280 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
176 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
472 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 ...
6
votes
3answers
211 views
6
votes
3answers
183 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
115 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
332 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 ...
5
votes
1answer
288 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
3answers
118 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: ...
5
votes
0answers
161 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
0answers
152 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
326 views

Using units and piecewise functions in Integrate

For simple cases, Quantities appear to be handled well by Integrate: ...
4
votes
2answers
358 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
1answer
141 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 ...
3
votes
3answers
239 views

How to deal with units in logarithms?

I'm trying to take a formula, take it's integral which yields a formula with logarithms, and then directly plug in values with units and get an answer. However if the units go into any of the ...
3
votes
2answers
100 views

Something wrong with the way units are handled in V10

(This applies only to version 10) I obtain these two properties of silicon: a = ElementData[14, "CrustAbundance"] b = ElementData[14, "MeteoriteAbundance"] both ...
3
votes
1answer
123 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?
3
votes
1answer
585 views

Unit issues in Mathematica 9

I posted the following on the Google+ group comp.soft-sys.math.mathematica and had no luck with responses. I've done a Google search and, to the best of my ability, ...
3
votes
3answers
209 views

Inputting abbreviated units [duplicate]

Possible Duplicate: Simpler input for the new unit support Is there a way to input abbreviated units directly from the keyboard? One can get a value with abbreviated units through the ...
3
votes
2answers
724 views

Units, plotting and empty plots

maybe I'm completely newbie but I can't understand the behavior of units and the command plot. I'm doing some easy plotting of the state equation for gasses: ...
3
votes
1answer
67 views

Is there a way to display units in short label?

For example, forQuantityUnit[Quantity[1, "Meters"]], is there a way to display the results as"m" instead of "Meters"?
3
votes
1answer
224 views

Why cant Mathematica 9 interpret this unit?

I'm using Mathematica 9.0.1. Sorry for using an image, but pasting code messed up the output formatting. I'd like to represent 25 Btu/(hr ft F). All units are spelled correctly as identified in ...
3
votes
1answer
448 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 ...
3
votes
1answer
159 views

Wavelength, wavenumber, energy and frequency in a ruler

I would like to generate set of four axis relating wavelength, wavenumber, energy and frequency in an arbitrary range. Like in this image but without the labels such as "RADAR". The selection of ...
3
votes
1answer
104 views

Choosing the units for plotting

I´m new to using units in Mathematica. I have read other similar posts about this issue but I haven´t found an answer so far. My problem is simple: I want to plot a certain function with a certain ...
2
votes
2answers
99 views

Calculations with physical units [closed]

I really don’t get the Units in Mathematica 9. to work. I have tried this in the past for several times and at the end always run into some troubles. For example ...
2
votes
2answers
132 views

How to specify units for ImageSize Option? [duplicate]

I'm trying out making a CDF and I want it to print within the margins of Letter paper. There is an ImageSize option that I would like to set; some plots will be in ...
2
votes
1answer
339 views

How to get the quantity of Physical constants?

I need to get the quantity of gravitational constant: QuantityMagnitude[GravitationalConstant] why this is not work? Already load the ...
2
votes
2answers
634 views

Use of own unit abbreviations

I have been using AutomaticUnits in my calculations. In this package all I had to do was to declare the units I wanted e.g. mm, kN, sec, kPa, litres etc. in terms of existing units, and then use them ...
2
votes
1answer
191 views

UnitSimplify returns unexpected non-SI unit combination

I am trying to get units working in mathematica in the following expression for diffusion: $D = {K_B T}/{3 \pi \eta L}$ My code is as follows: ...
2
votes
4answers
120 views

Cancelling units in two-argument ArcTan

Consider ArcTan[3, -3] (* out: *) -Pi/4 ArcTan[3 a Sin[t/2], -3 a Sin[t/2]] (* out: *) ArcTan[3 a Sin[t/2], -3 a Sin[t/2]] However, we can fix the ...
2
votes
1answer
92 views

Using Manipulate[ ] with physical units

I'm a new user, and am trying to build a simple Boyle's law system in Mathematica. I want to include the units of the values, as I may need to perform some conversions later. If my quantities are a ...
2
votes
1answer
78 views

Converting in various currencies

I was just playing around with Mathematica converting some currencies: ...
2
votes
1answer
326 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: ...
2
votes
0answers
71 views

Quantities formatting problem

So I've developed this simple code ...
2
votes
0answers
89 views

Is it possible to use Gaussian cgs units in $Mathematica$ computations?

I was trying to do computations in Gaussian cgs units, and of course I failed due to dimensional issues. For instance, $q_1 q_2/r$ cannot be converted to $\mathrm{erg}$ since Gaussian system uses ...
2
votes
0answers
75 views

List of supported units in Mathematica 9 [duplicate]

Is there a list of supported units in Mathematica 9 documentation? I personal haven't found any; even the physical constants (newly supported as units in 9) can only be found in compatibility ...
1
vote
1answer
92 views

Solving equations with QuantityVariable

I'm trying to understand how to easily solve equations that use QuantityVariable. Why does this fail? ...