Sin, cos etc for Python 2 Decimal? -

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in python 2.6, found decimal equivalent of sqrt(pi) is

decimal(pi).sqrt()

is there sin, cos or other (inverse) trigonometric functions?

the docs mention how calculate cos , sin computationally. decimal(pi).cos() doesn't exist nor from decimal import cos

update: problem using default trigonometric functions defeats point of using decimal if convert them float , every time want calculate something. (also typing decimal around every calculation annoying, guess make wrapper function)

values of sin(a) , cos(a) rational numbers particular angles (see http://planetmath.org/encyclopedia/rationalsineandcosine.html ) can't store values of sin(a) or cos(a) decimals without losing precision. defeats purpose of converting sin , cos values decimal , having built-in functions return sin , cos values decimals.

moreover, can't store rational numbers decimal without losing precision because python's decimals (-1)**_sign * _int * 10**_exp divisor of rational number must 10 decimal store full precision.

i guess @carrot-top's mpmath advice or numeric algorithm (like taylor series approximation) best can get.


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