C Programming (Turbo / Visual C++ Compiler) - Using Cosine Series to find COS Value
I have given here a C program to find the value of cos using Cosine Series and without using the library function. This program will print the values got from the series function MyCos and library function cos.
Cosine series = 1 - x^2/2! + x^4/4! - x^6 / 6! + x^8 / 8! - .....
Source Code
#include <math.h>
#include <stdio.h>
const double PI = 3.14159265;
// cos series = 1 - x^2/2! + x^4/4! - x^6 / 6!
double MyCos(double x)
{
double sqx = x * x;
double cosineresult = 1;
double fact = 2;
int index = 2;
int term = 0;
double termfactor = 0;
for(term = 1; term < 20; term++)
{
termfactor = 0;
termfactor = sqx / fact;
if(term %2)
{
cosineresult = cosineresult - termfactor;
}
else
{
cosineresult = cosineresult + termfactor;
}
index++;
fact *= index;
index++;
fact *= index;
sqx *= (x*x);
}
return cosineresult;
}
int main()
{
double i = 0;
for(i = 0; i <= 360; i += 4.75)
{
printf("%.4lf = %.4lf\t%.4lf\n", i, cos(i * PI / 180), MyCos(i * PI / 180));
//printf("%.4lf\n", cos(i * PI / 180) - MyCos(i * PI / 180));
}
return 0;
}
Output
0.0000 = 1.0000 1.0000
4.7500 = 0.9966 0.9966
9.5000 = 0.9863 0.9863
14.2500 = 0.9692 0.9692
19.0000 = 0.9455 0.9455
23.7500 = 0.9153 0.9153
28.5000 = 0.8788 0.8788
33.2500 = 0.8363 0.8363
38.0000 = 0.7880 0.7880
42.7500 = 0.7343 0.7343
47.5000 = 0.6756 0.6756
52.2500 = 0.6122 0.6122
57.0000 = 0.5446 0.5446
61.7500 = 0.4733 0.4733
66.5000 = 0.3987 0.3987
71.2500 = 0.3214 0.3214
76.0000 = 0.2419 0.2419
80.7500 = 0.1607 0.1607
85.5000 = 0.0785 0.0785
90.2500 = -0.0044 -0.0044
95.0000 = -0.0872 -0.0872
99.7500 = -0.1693 -0.1693
104.5000 = -0.2504 -0.2504
109.2500 = -0.3297 -0.3297
114.0000 = -0.4067 -0.4067
118.7500 = -0.4810 -0.4810
123.5000 = -0.5519 -0.5519
128.2500 = -0.6191 -0.6191
133.0000 = -0.6820 -0.6820
137.7500 = -0.7402 -0.7402
142.5000 = -0.7934 -0.7934
147.2500 = -0.8410 -0.8410
152.0000 = -0.8829 -0.8829
156.7500 = -0.9188 -0.9188
161.5000 = -0.9483 -0.9483
166.2500 = -0.9713 -0.9713
171.0000 = -0.9877 -0.9877
175.7500 = -0.9973 -0.9973
180.5000 = -1.0000 -1.0000
185.2500 = -0.9958 -0.9958
190.0000 = -0.9848 -0.9848
194.7500 = -0.9670 -0.9670
199.5000 = -0.9426 -0.9426
204.2500 = -0.9118 -0.9118
209.0000 = -0.8746 -0.8746
213.7500 = -0.8315 -0.8315
218.5000 = -0.7826 -0.7826
223.2500 = -0.7284 -0.7284
228.0000 = -0.6691 -0.6691
232.7500 = -0.6053 -0.6053
237.5000 = -0.5373 -0.5373
242.2500 = -0.4656 -0.4656
247.0000 = -0.3907 -0.3907
251.7500 = -0.3132 -0.3132
256.5000 = -0.2334 -0.2334
261.2500 = -0.1521 -0.1521
266.0000 = -0.0698 -0.0698
270.7500 = 0.0131 0.0131
275.5000 = 0.0958 0.0958
280.2500 = 0.1779 0.1779
285.0000 = 0.2588 0.2588
289.7500 = 0.3379 0.3379
294.5000 = 0.4147 0.4147
299.2500 = 0.4886 0.4886
304.0000 = 0.5592 0.5592
308.7500 = 0.6259 0.6259
313.5000 = 0.6884 0.6884
318.2500 = 0.7461 0.7461
323.0000 = 0.7986 0.7986
327.7500 = 0.8457 0.8457
332.5000 = 0.8870 0.8870
337.2500 = 0.9222 0.9222
342.0000 = 0.9511 0.9511
346.7500 = 0.9734 0.9734
351.5000 = 0.9890 0.9890
356.2500 = 0.9979 0.9979
Press any key to continue . . .
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