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Making Arctan function with CORDIC algorithms

P: 10
i`m doing thesis about comparing calculation of arctan by polynomial and CORDIC. I`ve read a lot of journal and books about CORDIC and this is what i understand.

1. make x and y
2. make iterations
3. process with cordic calculation
4. the arctan result is calculating by arctan(y/x).

what i m confused that in cordic equation there`s

Zi=Zo-arctan(2^-i)

i can do Z=0 , but how can i get arctan(2^-i) values? from what i m reading that it come from arctan tables? how can i make arctan tables?

and let say i m looking arctan(0.1) = ...

is that mean that i have to set the X=1 and the Y =0.1 ???

i m not that good in programming.
anyone can help me?

ps. i`m using borland c++ builder
Feb 5 '07 #1
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4 Replies


Expert 100+
P: 1,510
i`m doing thesis about comparing calculation of arctan by polynomial and CORDIC. I`ve read a lot of journal and books about CORDIC and this is what i understand.

1. make x and y
2. make iterations
3. process with cordic calculation
4. the arctan result is calculating by arctan(y/x).

what i m confused that in cordic equation there`s

Zi=Zo-arctan(2^-i)

i can do Z=0 , but how can i get arctan(2^-i) values? from what i m reading that it come from arctan tables? how can i make arctan tables?

and let say i m looking arctan(0.1) = ...

is that mean that i have to set the X=1 and the Y =0.1 ???

i m not that good in programming.
anyone can help me?

ps. i`m using borland c++ builder
which cordic equation are you using to determine arctan()? do you have a reference?

arctan can take two parameters, the X and Y coordinates, e.g. atan2()
http://cplusplus.com/reference/clibrary/cmath/atan2.html

or one parameter X / Y, e.g. atan()
http://cplusplus.com/reference/clibrary/cmath/atan.html
Feb 5 '07 #2

P: 10
which cordic equation are you using to determine arctan()? do you have a reference?

arctan can take two parameters, the X and Y coordinates, e.g. atan2()
http://cplusplus.com/reference/clibrary/cmath/atan2.html

or one parameter X / Y, e.g. atan()
http://cplusplus.com/reference/clibrary/cmath/atan.html


i`m counting arctan for one parameter using this equation

xi+1=xi+ - yi*2^-i
yi+1=yi+ - xi*2^-i
Zi+1=Zi+ - arctan (2^-i)

the plus n minus is depend on the Y value
Feb 5 '07 #3

Expert 100+
P: 1,510
i`m counting arctan for one parameter using this equation

xi+1=xi+ - yi*2^-i
yi+1=yi+ - xi*2^-i
Zi+1=Zi+ - arctan (2^-i)

the plus n minus is depend on the Y value
have you seen
http://www.voidware.com/cordic.htm
Feb 5 '07 #4

P: 10
have you seen
http://www.voidware.com/cordic.htm
thanks you a lot, it help me very much
Feb 7 '07 #5

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