How do calculators calculate trig function?

In summary, calculators use a method called CORDIC, which is faster than evaluating Taylor polynomials, for calculating trigonometric functions. This method reduces chip size, making it more efficient for calculators. Computers, on the other hand, use range reduction algorithms combined with minimax polynomials, which are even faster and more accurate. These techniques are not commonly taught in schools but can be learned through online resources or books such as "Computer Approximations" by Hart, Cheney, and Lawson. This book was written in the 1960s and is a classic reference for these methods.
  • #1
Superposed_Cat
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Hi I was wondering how calculators calculate trigonometric functions. Do they use taylor polynomials(if so what order) or what? any help appreciated.
 
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They use a method called CORDIC, which is much faster than evaluating Taylor polynomials:

http://www.qc.cuny.edu/Academics/Degrees/DMNS/Faculty%20Documents/Sultan1.pdf
 
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  • #3
SteamKing said:
They use a method called CORDIC, which is much faster than evaluating Taylor polynomials.
And range reduction algorithms combined with minimax polynomials are even faster.

A computer is more likely to use range reduction algorithms combined with minimax polynomials, a calculator, CORDIC. Calculators use CORDIC because it reduces chip size. Computers use range reduction and minimpax polynomials because they are fast and accurate. *Nobody* in their right mind uses Taylor series.
 
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  • #4
could you send me a link DH? I did google it but nothing I could see off a cursory look.
 
  • #7
Thanks, is there a place that online that i can learn from? i don't want to buy a book on it.
 
  • #8
you guys are great I always wondered how calculators do calculations, where did you guys learn about these books? was it in school or by word of mouth? do these books reflect your age? 1960's computer scientists? lol
 

1. How do calculators calculate trigonometric functions like sine and cosine?

Calculators use a series of mathematical formulas and algorithms to calculate trigonometric functions. These formulas are based on the ratios of the sides of a right triangle and involve the use of basic operations such as addition, subtraction, multiplication, and division.

2. Are there different methods or algorithms used by different calculators to calculate trigonometric functions?

Yes, there are different methods and algorithms used by different calculators to calculate trigonometric functions. Some calculators use Taylor series or Maclaurin series to approximate the values of trigonometric functions, while others use lookup tables or specialized hardware to perform these calculations.

3. How accurate are the trigonometric function calculations performed by calculators?

The accuracy of trigonometric function calculations performed by calculators depends on the method or algorithm used. Generally, most calculators provide accurate results up to a certain number of decimal places, but there may be slight variations due to rounding errors or limitations of the hardware used.

4. Can calculators calculate trigonometric functions for non-right triangles?

Yes, some calculators have the ability to calculate trigonometric functions for non-right triangles. This is done by using the law of cosines or the law of sines to determine the missing sides or angles of the triangle, and then applying the appropriate trigonometric function formula.

5. Do calculators use the same method to calculate inverse trigonometric functions?

No, calculators use different methods to calculate inverse trigonometric functions. Some use power series expansion, while others use iterative methods or special algorithms. However, the end result is the same - to find the angle whose trigonometric function value is known.

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