Mobile App

[amendale]

Is anyone familiar of a mobile app that can do operations with common engineering units?
For example doing something like this would be great:
sqrt(5 W/5 Ohms) = 1.58 A

 

[VEBill]

Wolfram Alpha, although it gives the answer 1.00 Amp.

 

[MacGyverS2000]

Have basic calculators fallen out of use?

On that note, has basic math in your head fallen out of fashion? 5 of anything divided by 5 of anything else is 1 of something. Square root of that had better be 1 of something else.

You should know what units are going into an equation as well as what units to expect out.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[IRstuff]

Nonetheless, the square root of an ampere does not make much sense.

SMath Studio would be the best bet, but the author still doesn't seem to want to go there:

http://en.smath.info/forum/default.aspx?g=posts&t=1120

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[amendale]

I meant to write:
sqrt(5 W/2 Ohms) = 1.58 A

Sorry guys. SMath doesn't have that capability on the mobile version does it?

 

[IRstuff]

sorry, my bad; brain fart on the square root.


SMath is only available for PPC-based devices, and hasn't been updated to the latest rev.

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[VEBill]

Again: Wolfram Alpha - a very famous mobile app.

Here's a screen capture from my phone just now...

 

[ewh]

You have cross-posted to two fora that I've seen, and Wolfram Alpha seems the best solution in both.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[VEBill]

I should mention that the Wolfram Alpha 'app' requires a network connection back to the server.

 

[electricpete]

Personally I would use Droid48 for Android (or the similar HP48 emulator for iPhone).

No connection required.

A big HP team back in the day invested a whole lot of time developing a pretty sophisticated math programming environment which was easily accessible through a tiny interface. Their efforts still pay off today imo. There are some ups and downs. Downs include a little bit of a learning curve and limited graphics. Ups are many... instead of getting carried away on those, I'll just link to my previous discussion here:

thread724-313111

=====================================
(2B)+(2B)' ?

 

[VEBill]

Calculators generally don't include units in their calculations. Carrying the units through the calculation can be extremely useful.

In the Wolfram Alpha screenshot above, you can see that it has correctly calculated not only the value "1.581" but also the correct units "A (amperes)". That's cool.

 

[electricpete]

Yes, the HP48 does unit-aware calculations. You can enter mixed units in an equation and convert the result to whatever unit you want.

=====================================
(2B)+(2B)' ?

 

[VEBill]

I should also point out that Google will respond correctly to the example given.

Google: sqrt(5 watts / 2 ohms)

Response: sqrt((5 watts) / (2 ohms)) = 1.58113883 amperes

The online calculators can also tell you such nonsense as:
26 Parsecs = 4.71428 × 10¹⁷ smoots
(I'll let you look-up the definition of a smoot)

 

[electricpete]

Attached are three easy ways to solve the problem with HP48:
1 - RPN
2 – Algebraic
3 - Solve Dialogue.

The solve dialogue works with stored equations and variables, or creates them if they are not available. Named equations and named variables are stored in nested subdirectories, so you can build your own library of equations, and copy variable values or equations between subdirectories if you want. Structured programming is supported, along with a ton of built in math tools (see the link)

The built in units do not include smoot unfortunately ;-), but there is a capability to add user defined units.

The screens in the attached powerpoint came from the free PC program HPuseredit (version 4) which coordinates with free PC HP48 emulator program Emu48. You can use these tools to build and debug programs on pc and transfer to phone if you are so inclined. And of course Droid48 is also free.

I like it a lot, enough that I enjoy telling other people about it. I’m not saying it’s the best for this purpose or the best for any purpose… these things are matters of personal preference.

I’ve never tried Wolfram.


=====================================
(2B)+(2B)' ?

 

[VEBill]

I’ve never tried Wolfram.

Gasp!

You're quite talented in math, and yet you've not yet tried Wolfram Alpha?

I think you'd like it. Like Google Calculator, it has smoots. But it's vastly more capable. It is also filled with vast amounts of real world data.

 

[IRstuff]

I did have great hopes for it when it first rolled out, but every time I've asked it for stuff, it was unable to deliver anything useful. Since I always have Mathcad open, I don't need another math tool.

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[zappedagain]

I'll second that for MathCAD. Bummer it is still so expensive. It looks like they have a new free version though, too bad it isn't portable:

http://www.engineering.com/DesignSo...s-Giving-Away-Mathcad-Express-Pass-it-on.aspx

 

[IRstuff]

Mathcad Prime 3.0, which succeeds the 2.0 version in the cited link, is now available:

http://communities.ptc.com/message/222302

As with MP2.0, you can get a free license to use the full capabilities for 30 days, after which it reverts to the free version, with a limited capability. That said, MP3/MP2 Express do contain sufficient capability to do lots of engineering calculations.

TTFN
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