JavaCard OS

Posted: **Tue Sep 26, 2017 2:27 pm**

Hello everyone,
I want to calculate sinus and cosinus in javacard. what is the best and fastest solution?
Thank a lot.

Posted: **Tue Sep 26, 2017 11:55 pm**

Just try to use Look-up table method.

Define an array with size 360 bytes, direct look up the table to calculate sinus and cosinus.

Posted: **Wed Sep 27, 2017 1:43 am**

mabel wrote:Just try to use Look-up table method.

Define an array with size 360 bytes, direct look up the table to calculate sinus and cosinus.

Thank you very much mabel.

Posted: **Wed Sep 27, 2017 2:06 am**

mabel wrote:Just try to use Look-up table method.

Define an array with size 360 bytes, direct look up the table to calculate sinus and cosinus.

It's indeed a good method. But there is still a problem. Look-up table method is available for integer angle. If you need to handle the angle with decimals, this method is not a good one.

Posted: **Wed Sep 27, 2017 5:36 am**

Maybe use a factor can solve your problem,e.g:sin1 => sin1*500, and you'll get the array like this:

Code: Select all

SIN[] =
{
    0, 8, 17, 26, 35, 44, 53, 62, 71, 80, 88, 97, 106, 115, 123, 132, 141, 149, 158,
    166, 175, 183, 191, 200, 208, 216, 224, 232, 240, 248, 255, 263, 271, 278, 286,
    293, 300, 308, 315, 322, 329, 335, 342, 349, 355, 362, 368, 374, 380, 386, 392,
    397, 403, 408, 414, 419, 424, 429, 434, 438, 443, 447, 452, 456, 460, 464, 467,
    471, 474, 477, 481, 484, 486, 489, 492, 494, 496, 498, 500, 502, 504, 505, 507,
    508, 509, 510, 510, 511, 511, 511, 512, 511, 511, 511, 510, 510, 509, 508, 507,
    505, 504, 502, 500, 498, 496, 494, 492, 489, 486, 484, 481, 477, 474, 471, 467,
    464, 460, 456, 452, 447, 443, 438, 434, 429, 424, 419, 414, 408, 403, 397, 392,
    386, 380, 374, 368, 362, 355, 349, 342, 335, 329, 322, 315, 308, 300, 293, 286,
    278, 271, 263, 255, 248, 240, 232, 224, 216, 208, 200, 191, 183, 175, 166, 158,
    149, 141, 132, 123, 115, 106, 97, 88, 80, 71, 62, 53, 44, 35, 26, 17, 8, 0, -8,
    -17, -26, -35, -44, -53, -62, -71, -80, -88, -97, -106, -115, -123, -132, -141,
    -149, -158, -166, -175, -183, -191, -200, -208, -216, -224, -232, -240, -248,
    -256, -263, -271, -278, -286, -293, -300, -308, -315, -322, -329, -335, -342,
    -349, -355, -362, -368, -374, -380, -386, -392, -397, -403, -408, -414, -419,
    -424, -429, -434, -438, -443, -447, -452, -456, -460, -464, -467, -471, -474,
    -477, -481, -484, -486, -489, -492, -494, -496, -498, -500, -502, -504, -505,
    -507, -508, -509, -510, -510, -511, -511, -511, -512, -511, -511, -511, -510,
    -510, -509, -508, -507, -505, -504, -502, -500, -498, -496, -494, -492, -489,
    -486, -484, -481, -477, -474, -471, -467, -464, -460, -456, -452, -447, -443,
    -438, -434, -429, -424, -419, -414, -408, -403, -397, -392, -386, -380, -374,
    -368, -362, -355, -349, -342, -335, -329, -322, -315, -308, -300, -293, -286,
    -278, -271, -263, -256, -248, -240, -232, -224, -216, -208, -200, -191, -183,
    -175, -166, -158, -149, -141, -132, -123, -115, -106, -97, -88, -80, -71, -62,
    -53, -44, -35, -26, -17, -8, 0
};

Posted: **Wed Sep 27, 2017 5:54 am**

To handle the angle with decimals, try to use this formula
sin(a+b) =sina*cosb+cosa*sinb
cos(a+b) = cosa*cosb - sina*sinb

Take angle 45.5 as an example,

sin(45+0.5) = sina45*cos0.5 + cos45*sin0.5

But you may need to define 4 arrays sin[0~360], cos[0~360], sin[0.0~0.1],cos[0.0~0.1]

JavaCard OS

Sinus and Cosinus calculation in javacard?

Sinus and Cosinus calculation in javacard?

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