Questions about calculating with units in Mathematica.

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7
votes
2answers
164 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 ...
0
votes
1answer
54 views

Solving equations with QuantityVariable

I'm trying to understand how to easily solve equations that use QuantityVariable. Why does this fail? ...
1
vote
1answer
88 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
119 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 ...
2
votes
0answers
60 views

Quantities formatting problem

So I've developed this simple code ...
6
votes
3answers
179 views
0
votes
0answers
54 views

Meaning of backtick in conjunction with units [duplicate]

In this fragment from an equation solution the backtick is used twice: ...
0
votes
0answers
43 views

Fitting data involving units

I want to fit some data to a model. However, if the data involves units in the independent variable, fitting seems not to work. As an example, consider the code ...
2
votes
4answers
103 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 ...
0
votes
0answers
39 views

FindRoot with units error: Message text not found

This is sort of embarrassing. I'm working on a document to extol the virtues of Mathematica, and I can't get it to solve a relatively simple system of equations involving units. In this code, when I ...
0
votes
1answer
81 views

AstronomicalData not including units?

I like using mathematica to do my physics homework, and AstronomicalData is useful for that, but it doesn't seem to work properly with units. [the question is, at ...
2
votes
1answer
183 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: ...
-1
votes
2answers
114 views

Why won't Mathematica work with quantities or Quantity[]? [closed]

As you can see in the screenshot below, Mathematica is simply not evaluating any quantities. It is simply listing them as I wrote them. Could anybody give me a pointer as to why this may be?
7
votes
3answers
415 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 ...
-1
votes
1answer
75 views

Make Quantity behave reasonable with Degrees Celsius

When using a Quantity with the unit of "DegreesCelsius" multiplication doesn't work as expected. If you have 10 degrees and ...
3
votes
1answer
96 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 ...
1
vote
1answer
98 views

Multiplying SI Prefixes [closed]

I'm doing a few calculations and would like to keep my units straight. I figured that using the built-in Units functionality could help with this. However, using SI prefixes doesn't seem to give the ...
1
vote
1answer
195 views

Unit of the frequency axis in BodePlot

I have a simple question: What is the unit of the frequency axis in the BodePlot? I searched the documentation, but only found this: The scaling functions can be specified as ...
1
vote
1answer
84 views

Grouping units more sanely

Would it be possible to get Mathematica to group units more sanely. For example the calculation: ...
4
votes
2answers
239 views

Using units and piecewise functions in Integrate

For simple cases, Quantities appear to be handled well by Integrate: ...
5
votes
0answers
138 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\; ...
1
vote
1answer
228 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 ...
1
vote
1answer
102 views

Caching data in Mathematica package

Consider the following: m=Quantity[1,"meter"] If I run the package, it will return 1m But when I load the package, the ...
3
votes
1answer
209 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 ...
2
votes
0answers
76 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
1answer
282 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: ...
6
votes
3answers
169 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. ...
5
votes
0answers
96 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? ...
4
votes
2answers
318 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 ...
1
vote
1answer
69 views

Extract function parameters from “unevaluated” FormBox

I want to get the abbreviation for a Unit from its full name eg. "Newtons" => "N". Using ...
1
vote
0answers
81 views

Insert a Quantity Unit literal in TraditionalForm

Is there a keyboard shortcut for creating something like the result of this: Quantity["Kilograms" * ("Meters")^2 / ("Seconds")^2] After copying the result to a ...
3
votes
2answers
519 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: ...
1
vote
0answers
55 views

Will aliasing the Quantity and UnitConvert functions to “in” and “to” create problems?

It seems that there is a lot of interest in enhancing the use of units in Mathematica; various solutions in the name of brevity, correctness, and general utility have been demonstrated. I've begun ...
1
vote
0answers
118 views

How can I say that all quantities need to be positive (and real)? [duplicate]

Can you say at the beginning of a script in Mathematica that you want all the quantities to be positive (and real)? So that in all calculations, only the real values of these quantities will be ...
5
votes
0answers
146 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 ...
2
votes
0answers
72 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 ...
10
votes
1answer
310 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 ...
1
vote
1answer
748 views

Plotting with Units

I'm trying to get Mathematica to plot with units, but I'm having some trouble. Below is a minimal example of trying to plot y = x, where ...
10
votes
1answer
323 views

Kelvin per Kelvin Difference

I'm trying to use Mathematica units more often, but I've run into the following problem: ...
3
votes
3answers
230 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 ...
15
votes
2answers
496 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 ...
4
votes
1answer
134 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 ...
8
votes
1answer
260 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: ...
6
votes
0answers
318 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 ...
9
votes
1answer
949 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, ...
3
votes
1answer
532 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, ...
30
votes
4answers
2k views

Are Mathematica 9 units really slow?

This generates 75 unitized pairs for a plot that displays physical units: ...
5
votes
1answer
252 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?
9
votes
1answer
226 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 ...
3
votes
1answer
406 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 ...