Mixing scientific and normal notation

[Russell]

Hello all.

Is there any way to emulate what most calculators do, namely display numbers in normal decimal form, but switch to scientific form when the exponent is outside a certain range?

Failing that, is there any way to convert the last answer into scientific form?

Scientific mode is useless to me... I don't want 12 being rendered as 1.2e1 for example. But by the same token I am getting very sick of counting dozens of zeros in my answers.

Sometimes I divide by a guessed power of 10, or find log_10 of the answer, but neither is very convenient.

Thanks in advance

Russell

[Jim Fullerenex]

Well, you can use a program (a very simple one) to achieve it.

Prgm display(number)

 setmode(x,y)

// the parameters x and y depend on your desired scientific format. You can look it up in the Nspire Reference Guide.

Disp number

// input of the program 

EndPrgm

Best,

Jim

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[Dennis Donovan]

I'm using a CAS, not sure if the following is true on a Numeric.

The Nspire CAS can calculate alarmingly long integers (I don't know how many digits, but I'm sure someone does).  so if you type in something like

222222222222222222222222222222222222222222222222222*3333333333333333333333333333333333333333333333333333333333

The Nspire CAS will give you an integer result and all the digits.

740740740740740740740740740740740740740740740740739999999925925925925925925925925925925925925925925925925926

However if you type

222222222222222222222222222222222222222222222222222.*3333333333333333333333333333333333333333333333333333333333

(Notice the decimal point at the end of the 2's)

The Nspire CAS will display the result in Scientific notation

7.4074074074073E107

The Nspire CAS tries to be exact, but if you put in a decimal point, it thinks it is working with approximate values and will return an approximate calculation.

Give this a try and see if it gives you the results that you want.  If not, give us a specific calculation that you want to see a scientific result, that is not displaying that way.

BTW, if you want to create that display() program, the setmode command you want is setmode(3,2) for scientific notation.  While in the program editor, you can find the modes at: Menu -> Mode and all the selections are there ... you want Exponential Format -> Scientific.

Hope that helps.

Dennis

---

From: Jim Fullerenex <smoa...@gmail.com>
To: "tins...@googlegroups.com" <tins...@googlegroups.com>
Sent: Saturday, June 2, 2012 10:45 PM
Subject: Re: [tinspire] Mixing scientific and normal notation

[Russell]

Thanks guys for the replies so far.

On the non-CAS, if I type 1e-12, I get 0.0000000001, and 1e11 I get 100000000000. And anything with a smaller exponent than this is in normal form also.

A program doesn't really help, as I need to be able to tell my students how to do it, and putting programs in all their calculators merely to be able to perform simple calculations isn't really practical. Nor is counting heaps of tiny zeros off a screen, under the pressure of final exams.

Seems like a big boo boo to me if there is no way around this. Using scientific mode and putting up with silliness like 2e1 might be the least-bad option I guess.

Russell

[Dennis Donovan]

Are you running the latest software?  3.1.0.392 is the current software version, but 3.2 will be released soon (this month).  You can find this with Help->About in the software and Home->Settings->Status on the handheld.

Here are is a screen shot from a non-CAS in Float Mode.  Notice the difference between typing the numerator with and without a decimal point at the end of the number (I get the same result with the addition of the decimal point as I do with Ctrl-Enter on the fraction without the decimal point).  If I change to the default Float6 1E11 comes back as 1E11. 

Again, if you can give a screen shot or specific "calculations" that are not displaying as you want (and the specific mode that the handheld is in), that may help us.

Dennis

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From: Russell <russe...@gmail.com>
To: tins...@googlegroups.com
Sent: Sunday, June 3, 2012 7:49 AM
Subject: [tinspire] Re: Mixing scientific and normal notation

[Russell]

Ah ha - I think you've raised the pertinent point. Float-6.

I changed to Float-12 because it is very annoying when it rounds financial calculations round something like 12845.76 to 12845.80.

If I change back to Float-6, it will now switch to scientific notation mode when the exponent reaches 5 or -6.  So it seems like I have to suffer a compromise between rounding error or inconvenient display.  Playing with the TI-84 shows it switches around 10 for the exponent, which is quite large. But the difference is, the zeros are much bigger and easier to count.

I suppose the best advice to physics students is probably going to be to run in Scientific mode, or buy a scientific calculator and save the nspire for maths.

By the way, the decimal suffix is irrelevant for me, since I run in Approximate mode, to avoid those silly fractions. (If I wanted an exact answer, I wouldn't be using a calculator in the first place!)

Russell

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[Nevil Hopley]

Hello Russell, and others,

To help teachers & students better understand all the Settings on the Nspire that affect Science, Technology, Engineering and Maths, I created a STEM Calculator Guide to help.

You can find and download a copy from here:

http://resource.nspiringlearning.org.uk/classroomresources/activities/activity.jsp?id=369

When OS3.2 comes out, it may be that some of the screen shots will need to be updated, but for the moment, this might help you know what the effect of changing the numbers of digits will be, when in one of the various modes.

Nevil

[Sean Bird]

I generally recommend Float, because of the situation you said.

Even if you are using the Approx setting you will still get all the digits. However, if you use the ctrl enter it will give you your answer with the E (as in exponential entry).

See the images below.

Besides going to the home screen to change the settings, you could advice students to press doc in order to choose Scientific.

[Russell]

Thanks Bird.

I really despair that these calculators are overcomplicating things that calculators are designed to simplify.

I could just about work most sums out more quickly through long division than through mucking around with dozens of menus and rubbish.

I am an IB teacher, where CAS is prohibited... hopefully one day the IBO will prohibit all but simple scientific calculators and students will once more be able to concentrate on the mathematics rather than the user interface.

Russell

[Sean Bird]

Just to reiterate the simple answer to your original question...

Press CTRL ENTER

CTRL ENTER will easily switch an answer to scientific form when the exponent is outside a certain range. The 'certain range' is defined by the 'Float' or 'Fix' number of digits in the settings.

I'm glad testing organizations allow the use of the TI-Nspire or other graphing calculators so that math & science teachers are encouraged to have the students explore, understand, and explain topics graphically, numerically, algebraically, and verbally. Especially with the TI-Nspire there are numerous ready-to-use activities that require very little knowledge of the device where students can jump right into discovering the mathematics or simulating difficult to see science topics.

Hoping this sheds more light than heat,

Sean Bird