calculation problem

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#1)  calculation problem

Postby gnmcmartin » Thu Apr 15, 2010 10:06 pm

ENTS:

  I have bought measuring equipment and have been trying to learn how to use it.  I am not having any difficulty with the range finder or the clinometer—I think I am getting good data, although I may get better with practice.

  The problem is the calculator.  I have a Texas Instruments TI-30X IIS. The problem seems to be that I don’t know how to set the calculator so it can do the trig functions as described in Ed Frank’s step-by-step input sequence.  When I put in the angle from his example, 47 degrees, and then press the sin button, all I see is the left side of a parenthesis and a flashing upright rectangle, which I assume is like a computer cursor, telling me it is ready for more input rather than presenting me with the sin value.  I have experimented with pushing different buttons, but I get nothing.

  In the instructions for trig all it says is “enter trig functions (sin, cos, tan, sin -1, cos -1, tan -1), just as you would write them.  Set the desired angle mode before starting trig calculations.”

  I have done the latter, setting it for degrees.

  So, what am I missing here? Do I need a table of the sin values?  It seems the calculator is asking me for the sin number. But my understanding is that the calculator should present that to me so I can then multiply that by the distance from my eye to the tree top.

  --Gaines
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#2)  Re: calculation problem

Postby edfrank » Thu Apr 15, 2010 10:15 pm

Gaines,

Many Texas Instrument calculators use an input style calle RPN.  It was always so awkward and counter-intuitive to use, I opted to simply not use RPN calculators at all.  This is likely what is happening, and I can't tell you how to use that format of a calculator.  My calculator cost $9 with trig functions, so one solution would be t buy a calculator that doesn't use RPN.

Ed
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#3)  Re: calculation problem

Postby Beth » Thu Apr 15, 2010 10:30 pm

Gaines,

I have noticed that some calculators require you to put in the number then hit the trig function and some it the reverse hit the trig function then the number...examples....lets say your measurements are 20 degrees height at 30yds (90ft)  in the first case you would hit sin --> 20 --> X --> 90 = 30.78181289931.  The second case the sequence would be 20 --> sin --> X --> 90 = 30.78181289931.

Does that help?
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#4)  Re: calculation problem

Postby gnmcmartin » Thu Apr 15, 2010 11:35 pm

Beth:

  That's it!  If I enter the distance from my eye, then "sin," and then the angle, I get my answer.

  --Gaines
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#5)  Re: calculation problem

Postby James Parton » Fri Apr 16, 2010 5:55 am

Gaines,

I initially bought a Texas Instruments calculator and took it back. I did not like the way it worked. I have a Casio now and it works great!

James.
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#6)  Re: calculation problem

Postby dbhguru » Fri Apr 16, 2010 8:21 am

Gaines,

   The solution is a cheap Casio. Texas Instruments calculators are counter-intuitive. They're a royal pain. Casio calculators rule. TI calculators suck.

Bob
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#7)  Re: calculation problem

Postby gnmcmartin » Sat Apr 17, 2010 9:31 pm

Thanks for all the help/suggestions guys. I paid only about $12 at Walmart, and since Beth's changed input suggestion works, I am fine.  I won't use all the other functions on this thing, which would probably confuse me if I did.  Right now I am fine. I have been a little slow to get going with this measuring business because of time problems.  But this is fun--I hope I don't get a real bad case of some kind of measuring bug.

  I have some data to report--preliminary and sketchy as it may be. I will get to that as soon as I can get the data and the pics ready.

  --Gaines
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#8)  Re: calculation problem

Postby dbhguru » Sun Apr 18, 2010 4:16 pm

Gaines,

   Sorry, but we do hope you'll catch the measuring bug. We need data from your area, especially the West Virginia sites. We need examples of the best that you can find correlated to site factors such as moisture, soil, protection, etc. The value as Ents that we have, or potentially have, is best realized through the unique data that we collect and collate into useful lists and reports. The more data we collect and present, the bigger impact we will have.

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#9)  Re: calculation problem

Postby Don » Sun Apr 18, 2010 10:40 pm

Bob/Gaines-
While I've growled with others on calculators using RPL (I was always told it was Reverse Polish Logic, but now wonder if it wasn't an ethnic joke, not here intended), my current preferred 'tree height' calculator is my $30 Texas Instruments TI-30X II S.  Quite a title, but it's fairly basic.  What I like most about it, is it has enough screen display to contain significant portions of the formulas we use...that way, I get to more easily check my input data.  Comes in a hard case, with a clever hard cover.
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#10)  Re: calculation problem

Postby dbhguru » Mon Apr 19, 2010 7:35 am

Don,

   My understanding is that in early computer logics, it was easier for programmers to build software subroutines to do internal calculations using RPL. From my early days doing some machine and assembly language programming, a for sure masochistic practice, I'd say that would be true. Thank God, we're beyond those days.

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