﻿ C# - Using Cosine Series to find COS Value

# C# - 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 System.Math.Cos.

Cosine series = 1 - x^2/2! + x^4/4! - x^6 / 6! + x^8 / 8! - .....

## Source Code

using System;

using System.Collections.Generic;

using System.Text;

namespace SoftwareAndFinance

{

class Math

{

const double PI = 3.14159265;

// cos series = 1 - x^2/2! + x^4/4! - x^6 / 6!

public static 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) == 1)

{

cosineresult = cosineresult - termfactor;

}

else

{

cosineresult = cosineresult + termfactor;

}

index++;

fact *= index;

index++;

fact *= index;

sqx *= (x * x);

}

return cosineresult;

}

static void Main(string[] args)

{

for (double d = 0; d <= 360; d += 2.5)

{

Console.WriteLine("{0,6:f2} = {1,8:f5} {2,8:f5}", d, (double)System.Math.Cos(d * PI / 180.0), MyCos(d * PI / 180.0));

}

}

}

}

## Output

0.00 =  1.00000  1.00000

2.50 =  0.99905  0.99905

5.00 =  0.99619  0.99619

7.50 =  0.99144  0.99144

10.00 =  0.98481  0.98481

12.50 =  0.97630  0.97630

15.00 =  0.96593  0.96593

17.50 =  0.95372  0.95372

20.00 =  0.93969  0.93969

22.50 =  0.92388  0.92388

25.00 =  0.90631  0.90631

27.50 =  0.88701  0.88701

30.00 =  0.86603  0.86603

32.50 =  0.84339  0.84339

35.00 =  0.81915  0.81915

37.50 =  0.79335  0.79335

40.00 =  0.76604  0.76604

42.50 =  0.73728  0.73728

45.00 =  0.70711  0.70711

47.50 =  0.67559  0.67559

50.00 =  0.64279  0.64279

52.50 =  0.60876  0.60876

55.00 =  0.57358  0.57358

57.50 =  0.53730  0.53730

60.00 =  0.50000  0.50000

62.50 =  0.46175  0.46175

65.00 =  0.42262  0.42262

67.50 =  0.38268  0.38268

70.00 =  0.34202  0.34202

72.50 =  0.30071  0.30071

75.00 =  0.25882  0.25882

77.50 =  0.21644  0.21644

80.00 =  0.17365  0.17365

82.50 =  0.13053  0.13053

85.00 =  0.08716  0.08716

87.50 =  0.04362  0.04362

90.00 =  0.00000  0.00000

92.50 = -0.04362 -0.04362

95.00 = -0.08716 -0.08716

97.50 = -0.13053 -0.13053

100.00 = -0.17365 -0.17365

102.50 = -0.21644 -0.21644

105.00 = -0.25882 -0.25882

107.50 = -0.30071 -0.30071

110.00 = -0.34202 -0.34202

112.50 = -0.38268 -0.38268

115.00 = -0.42262 -0.42262

117.50 = -0.46175 -0.46175

120.00 = -0.50000 -0.50000

122.50 = -0.53730 -0.53730

125.00 = -0.57358 -0.57358

127.50 = -0.60876 -0.60876

130.00 = -0.64279 -0.64279

132.50 = -0.67559 -0.67559

135.00 = -0.70711 -0.70711

137.50 = -0.73728 -0.73728

140.00 = -0.76604 -0.76604

142.50 = -0.79335 -0.79335

145.00 = -0.81915 -0.81915

147.50 = -0.84339 -0.84339

150.00 = -0.86603 -0.86603

152.50 = -0.88701 -0.88701

155.00 = -0.90631 -0.90631

157.50 = -0.92388 -0.92388

160.00 = -0.93969 -0.93969

162.50 = -0.95372 -0.95372

165.00 = -0.96593 -0.96593

167.50 = -0.97630 -0.97630

170.00 = -0.98481 -0.98481

172.50 = -0.99144 -0.99144

175.00 = -0.99619 -0.99619

177.50 = -0.99905 -0.99905

180.00 = -1.00000 -1.00000

182.50 = -0.99905 -0.99905

185.00 = -0.99619 -0.99619

187.50 = -0.99144 -0.99144

190.00 = -0.98481 -0.98481

192.50 = -0.97630 -0.97630

195.00 = -0.96593 -0.96593

197.50 = -0.95372 -0.95372

200.00 = -0.93969 -0.93969

202.50 = -0.92388 -0.92388

205.00 = -0.90631 -0.90631

207.50 = -0.88701 -0.88701

210.00 = -0.86603 -0.86603

212.50 = -0.84339 -0.84339

215.00 = -0.81915 -0.81915

217.50 = -0.79335 -0.79335

220.00 = -0.76604 -0.76604

222.50 = -0.73728 -0.73728

225.00 = -0.70711 -0.70711

227.50 = -0.67559 -0.67559

230.00 = -0.64279 -0.64279

232.50 = -0.60876 -0.60876

235.00 = -0.57358 -0.57358

237.50 = -0.53730 -0.53730

240.00 = -0.50000 -0.50000

242.50 = -0.46175 -0.46175

245.00 = -0.42262 -0.42262

247.50 = -0.38268 -0.38268

250.00 = -0.34202 -0.34202

252.50 = -0.30071 -0.30071

255.00 = -0.25882 -0.25882

257.50 = -0.21644 -0.21644

260.00 = -0.17365 -0.17365

262.50 = -0.13053 -0.13053

265.00 = -0.08716 -0.08716

267.50 = -0.04362 -0.04362

270.00 =  0.00000  0.00000

272.50 =  0.04362  0.04362

275.00 =  0.08716  0.08716

277.50 =  0.13053  0.13053

280.00 =  0.17365  0.17365

282.50 =  0.21644  0.21644

285.00 =  0.25882  0.25882

287.50 =  0.30071  0.30071

290.00 =  0.34202  0.34202

292.50 =  0.38268  0.38268

295.00 =  0.42262  0.42262

297.50 =  0.46175  0.46175

300.00 =  0.50000  0.50000

302.50 =  0.53730  0.53730

305.00 =  0.57358  0.57358

307.50 =  0.60876  0.60876

310.00 =  0.64279  0.64279

312.50 =  0.67559  0.67559

315.00 =  0.70711  0.70711

317.50 =  0.73728  0.73728

320.00 =  0.76604  0.76604

322.50 =  0.79335  0.79335

325.00 =  0.81915  0.81915

327.50 =  0.84339  0.84339

330.00 =  0.86603  0.86603

332.50 =  0.88701  0.88701

335.00 =  0.90631  0.90631

337.50 =  0.92388  0.92388

340.00 =  0.93969  0.93969

342.50 =  0.95372  0.95372

345.00 =  0.96593  0.96593

347.50 =  0.97630  0.97630

350.00 =  0.98481  0.98481

352.50 =  0.99144  0.99144

355.00 =  0.99619  0.99619

357.50 =  0.99905  0.99905

360.00 =  1.00000  1.00000