Is there a command for arccosine?

stevenoo

hi,
··· Anyone know how to convert·an argument to an angle? for instant 'arccosin·x'. ·

Kirk Fraser

Since here we talk Stamps, the math must correspond to the integer math available in the Stamp Editor. Since my Win98SE on a Celeron somehow fails to look up Help when requested, I can't read the details of most commands in the PBASIC Syntax Guide easily but perhaps you can on your computer. I do see ATN is available. So if you need to work with trigonometry, you should find a text which gives the equivalent formulas to derive the function you want from the functions you have.

On the other hand, a solution to your problem as first stated without "arcosin x" you will have to examine the total picture to find a solution. For example, in my application I use data from 0 to 4095 to give degrees and tenths using a formula given by poster Tracy as x ** 57600 but I changed it to x ** 57615 to closer fit my data to desired results.

So it depends on exactly what you want in terms of both input values and angles output which requires more details for me to comprehend than you have provided.

Kirk

Tracy Allen

There is an ATN function that you can read about in the Stamp manual.

angle = x ATN y

where x and y are between -127 and +127 (representing +/- 1) and angle will be from 0 to 255 brads.

But you have x and want arccosine x. You can find y, and then plug it into the above formula.
On a unit circle, y*y = 1 - x*x. That is for a calculator, but on the Stamp for trig functions,
y = SQR (16384 - (x*x))
And
angle = x ATN (SQR (16384 - (x*x)))

For example, x=64, then y=111, angle = 42 brads.
In normal trig, that is x=0.5, y=sqr(3)/2, angle = 60 degrees, pi/3 radians.


edited: 60 degrees is ~42 brads

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Tracy Allen
www.emesystems.com

Post Edited (Tracy Allen) : 9/12/2006 5:21:01 AM GMT

dandreae

Kirk Fraser said...
Since here we talk Stamps, the math must correspond to the integer math available in the Stamp Editor. Since my Win98SE on a Celeron somehow fails to look up Help when requested, I can't read the details of most commands in the PBASIC Syntax Guide easily but perhaps you can on your computer. I do see ATN is available. So if you need to work with trigonometry, you should find a text which gives the equivalent formulas to derive the function you want from the functions you have.

On the other hand, a solution to your problem as first stated without "arcosin x" you will have to examine the total picture to find a solution. For example, in my application I use data from 0 to 4095 to give degrees and tenths using a formula given by poster Tracy as x ** 57600 but I changed it to x ** 57615 to closer fit my data to desired results.

So it depends on exactly what you want in terms of both input values and angles output which requires more details for me to comprehend than you have provided.

Kirk

Hi Kirk,
There is a work around for the "Help" file issue that you are experiencing.· If you click on "Start" in Windows and then click on "Programs" and then click on the "Parallax" folder you can open·the "Help" file from there.

Dave

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Dave Andreae

Tech Support
dandreae@parallax.com
Http://www.parallax.com

·

stevenoo

Thanks a lots guy.· Have a nice day.