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yanuart

Sin & Cos lookup table

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Hi, I''m using a fixed point math on my calculations with 24bits integral part and 8 bit fractions part. Can somebody tell me how to create a sin / cos lookup table with that precision for my trigonometry calculations ?? Thank you ...

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take your time:



#define DEGTORAD (M_PI/180)

typedef long fixed;

fixed sin_table[360],
cos_table[360];

void init_tables(void)
{
int i;
double val;

for(i = 0;i < 360;i++)
{
val = (double)i*DEGTORAD;
sin_table[i] = sin(val)*256;
cos_table[i] = cos(val)*256;
}
}



Cheers!

"Tonight we strike,there is thunder in the sky,together we''ll fight,some of us will die,but they''ll always remember that we''ve made a stand and many will die by hand!" - ManOwaR

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Yeah, the reason why I''m posting this thread is that I don''t have a sin function to generate sin value at the first place with the addition I don''t have a float data type !!,
Can somebody tell me how can I generate sin value using fixed point math ??

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Seriously, look into MacLaurin Series and Taylor Series. There are ways to build infinite geometric (or otherwise) series that converge on specific values of trigonometric functions.

Later,
ZE.

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just hardcode, its the easiest way.. if you want to just use a lookuptable anyways.

create the program on a platform where you have an fpu and sinf instruction, and let it output fixed sin[360] = { ...,..,..,..,.. }; and then copy paste that.

i''ve done that yet, too

"take a look around" - limp bizkit
www.google.com

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