Unit Conversion App Free Download
Celena Sessler
In human history, various unit systems were developed and used in different regions and cultures. Currently, the global standard of measurement is the International System of Units (SI), which is a modern form of the metric system. Although SI is intended for global use, it has not been fully adopted, and some other systems of measurement are still used in parts of the world.
The intent of this site is to provide a convenient means to convert between the various units of measurement within different systems, as well as to provide a basic understanding of the systems currently in use, and how they interact. Refer to the Common Unit Systems page for further information.
Dimensional analysis is a technique used to convert measurements. For example, changing the magnitude of a SI quantity or converting between SI and non-SI units. Some measurements have one dimension, for example length. A square shape (area) has two dimensions (e.g., length and width), while a cube (volume) has three dimensions (e.g., length, width, and height). Converting between measurement units is a very important skill when working within and between measurement systems.
This problem-solving method is based on the principle that quantities are defined as equalities. A conversion factor is an expression for the relationship between units that is used to change the units of a measured quantity without changing the value. A conversion ratio (or unit factor) always equals one (1), where the numerator and the denominator have the same value expressed in different units.
This method uses the fact that any number or expression can be multiplied by "one" without changing its value. This allows the conversion of units by multiplying the initial measurement by one (or more) forms of the number 1. While the multiplication by 1 does not change the value of the measurement, it does change the measurement units.
This process uses the fact that any number or expression can be multiplied by "one" without changing its value. This allows the conversion of units by multiplying the initial measurement by one (or more) forms of the number 1. While the multiplication by 1 does not change the value of the measurement, it does change the measurement units.
Many unit conversion problems will require only a single unit conversion factor. However, multiple factors may be required to solve a problem. These figures illustrate both examples. Remember that Step 3, identifying the conversion factor, is often the most challenging step. If an incorrect (or approximate) conversion factor is used, a correct solution will not be achieved.
The reason this issue arose in my case is because the getCoefficient(...) method in UnitConversionService stops as soon as it reaches a UnitConversion where both units on the conversion match the parameter units. As such, it is finding my Ton -> Pound conversion before my Pound -> Ton conversion, and inverting it, which uncovers the bug regarding the incorrect scale calculation. I have not tried removing my Ton -> Pound conversion to see if the coefficient for my Pound -> Ton is being properly scaled or not. I leave this to another exercise.
I can see this sort of thing being especially useful with units that are frequently changing, for example, file size units like Kb, Mb, Gb (as well as Kib, Mib, Gib, which are useful but often inconvenient to work with) are often most useful to list in their largest unit sizes. E.g. 5200 Mb is more parsimonious as 5.2Gb, .034 Mb as 34 Kb.
This would be hugely helpful in a problem I am trying to solve. My goal is to create a recipe database with multiple units of measure based off a conversion table. For example, if Butter is entered into the table with a unit of measure of pounds, I would be able to use all other weight units of measure (oz/wt, grams, Kg, etc.)
You can define 2 unit systems: one is the default you're (usually) writing your recipes in and the other one is the unit system you'd want to convert to. For each unit system you can set the name you want to display to your visitors and the different units that system is supposed to use.
For each unit system you can also pick the exact cup and spoon types that system uses. There's quite a difference between a Japanese and Metric cup, for example, so even if both systems use "cups", the quantity might have to change.
We integrate with an external API so the plugin knows that 1 cup of water is not the same quantity as 1 cup of rice in metric units. After calculation you still have full control over the values shown, so feel free to adjust to your liking.
It's not possible to set up unit conversion for all recipes at once. The problem is that an automated solution is never perfect. By manually going through the steps you can double check the unit it converts to, adjust that unit when needed or fix/round any quantities as required.
I'm working on a project that lets users track different data types over time. Part of the base idea is that a user should be able to enter data using any units that they need to. I've been looking at both units:
I applaud use of explicit units in scientific computing applications. Using explicit units is analogous brushing your teeth. It adds some tedium up front, but the type safety you get can save a lot of trouble in the long run. Like, say, not crashing $125 million orbiters into planets.
I ended up writing my own python package for unit conversion and dimensional analysis, but it is not properly packaged for release yet. We are using my unit system in the python bindings for our OpenMM system for GPU accelerated molecular mechanics. You can browse the svn repository of my python units code at:
Eventually I intend to package it for distribution. If you find it interesting, please let me know. That might motivate me to package it up sooner. The features I was looking for when I was designing the SimTK python units system included the following:
The benchmarks are disappointing for anyone obsessed with performance. :-( The slowdown of calculations with any of these unit systems is large. The slowdown factor is 6-10 for arrays with 1000 entries (worse for smaller arrays).
It's well maintained, easy to use, and has all the basic units (as well as astrophysics-related units).It provides tools for both units and quantities. And there's also a module for physical constants.
While it does have support for creating "random" units from computation (such as Pint, unum, etc), it's more tailored to having a database of units (which the library has by default -- see: and the implementation: ) and then you can query and transform based on the related units.
One thing it supports that does a lot of difference in that regard is dealing with unit conversions which would be "dimentionless" -- such as m3/m3 (i.e.:volume per volume) and then converting to cm3/m3 and keeping the dimension.
My preferred package is QuantiPhy. It takes a different approach than most other packages. With QuantiPhy the units are simply strings, and the package is largely used when reading or writing quantities. As such, it much easier to incorporate into your software. QuantiPhy supports unit and scale factor conversion both when creating quantities and when rendering them to strings. Here is an example that reads and then writes a table of times and temperatures, converting from minutes/F to seconds/K on the way in and back to the original units on the way out:
I find the units packages to be more than what want. It doesn't take much code to start building your own functions that refer back to the very few basic fundamental numbers. Also, It forces you to do the dimensional analysis to prevent errors.
Then let's say you want to plot the static head pressure of 1,3 Butadiene @44 F and use gauges in PSI because you live in the US but the density tables are in SI units as they should be........................
I'm new to Alfred's power after having used it for some time and excited at realizing how much it can do! I appreciate the built-in calculator function, but is there anything out there that can allow for quick unit conversions, such as kilograms to pounds, millimeters to inches, celsius to fahrenheit, etc?
I would start with a hashtable (or persisted lookup table - your choice how you implement) that carries unit conversions between as many pairs as you care to put in. If you put in every possible pair, then this is your brute force approach.
In this case, the keys are understanding that we are talking about units of length, so why don't we insert a new column into the table for unit type, which can be "length" or "area". This will help performance even in the earlier cases as it gives you an easy column to pare down your search space.
As has already been suggested, you should establish what the base set of units you are going to use are, and the SI base units immediately suggest themselves. Your data structure(s) for modelling units would then be defined in terms of those base units. You might therefore define a table (thinking RDBMS here, but easily translatable into your preferred implementation) with entries such as:
and so forth. You'll also need a table to translate prefixes (kilo-, nano-, mega-, mibi- etc) into multiplying factors, and a table of base units for each of the dimensions (ie meter is the base unit for Length, second for Time, etc). You'll also have to cope with units such as feet which are simply synonyms for other units.
I'm trying to veer away from suggesting (implementation-specific) solutions so I'll waffle a bit more. Compound units, such as kilowatt-hours, do pose a problem. One approach would be to tag measurements with multiple unit-expressions, such as kilowatt and hour, and a rule for combining them, in this case multiplication I could see this getting quite hairy quite quickly. It might be better to restrict the valid set of units to the most common ones in the domain of the application.
As to dealing with measurements in mixed units, well the purpose of defining the Dimension of a unit is to provide some means to ensure that only sensible operations can be applied to measurements-with-units. So, it's sensible to add two lengths (L+L) together, but not a length (L) and a volume (L^3). On the other hand it is sensible to divide a volume by a length (to get an area (L^2)). And it's kind of up to the application to determine if strange units such as kilowatt-hours per square metre are valid.
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