Microsoft KB Archive/157950

= How to use trigonometry STL functions in Visual C++ =

Article ID: 157950

Article Last Modified on 8/11/2005

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APPLIES TO

 The Standard C++ Library, when used with:  Microsoft Visual C++ 4.2 Enterprise Edition

 Microsoft Visual C++ 5.0 Enterprise Edition

 Microsoft Visual C++ 6.0 Enterprise Edition

 Microsoft Visual C++ 4.2 Professional Edition</li></ul>

 Microsoft Visual C++ 5.0 Professional Edition</li></ul>

 Microsoft Visual C++ 6.0 Professional Edition</li></ul>

 Microsoft Visual C++ 6.0 Standard Edition</li></ul>

 Microsoft Visual C++ .NET 2002 Standard Edition</li></ul>

 Microsoft Visual C++ .NET 2003 Standard Edition</li></ul> </li></ul>

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This article was previously published under Q157950

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NOTE: Microsoft Visual C++ NET (2002) supported both the managed code model that is provided by the .NET Framework and the unmanaged native Windows code model. The information in this article applies to unmanaged Visual C++ code only.

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SUMMARY
The sample code below illustrates how to use the STL acos, asin, atan, atan2, cos, cosh, sin, sinh, tan, tanh functions in Visual C++.

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Prototype
// acos template<class T>    inline valarray<T> acos(const valarray<T>& x);

// asin template<class T>    inline valarray<T> asin(const valarray<T>& x);

// atan template<class T>    inline valarray<T> atan(const valarray<T>& x);

// atan2 template<class T>    inline valarray<T> atan2(const valarray<T>& x, const valarray<T>& y);

template<class T>    inline valarray<T> atan2(const valarray<T> x, const T& y);

template<class T>    inline valarray<T> atan2(const T& x, const valarray<T>& y);

// cos template<class T>    inline valarray<T> cos(const valarray<T>& x);

// cosh template<class T>    inline valarray<T> cosh(const valarray<T>& x);

// sin template<class T>    inline valarray<T> sin(const valarray<T>& x);

// sinh template<class T>    inline valarray<T> sinh(const valarray<T>& x);

// tan template<class T>    inline valarray<T> tan(const valarray<T>& x);

// tanh template<class T>    inline valarray<T> tanh(const valarray<T>& x); NOTE: The class/parameter names in the prototype may not match the version in the header file. Some have been modified to improve readability.

Description
This article illustrates the use of STL trigonometry functions through sample code.

Sample Code
////////////////////////////////////////////////////////////////////// // // Compile options needed: /GX // // main.cpp : Illustrates the use of STL trigonometry functions. // // Functions: // // acos, asin, atan, atan2, cos, cosh, sin, sinh, tan, tanh // // Written by Yeong-Kah Tam // of Microsoft Product Support Services, // Copyright (c) 1996 Microsoft Corporation. All rights reserved. //////////////////////////////////////////////////////////////////////


 * 1) include                // for i/o functions
 * 2) include                // for valarray
 * 3) include                   // for trigonometry functions

using namespace std; // std c++ libs implemented in std #endif
 * 1) if _MSC_VER > 1020  // if VC++ version is > 4.2
 * 1) define ARRAY_SIZE 3               // array size

void main

{

// Initialize val_array to values -1, 0 and 1. valarray val_array(ARRAY_SIZE); for (int i = 0; i < ARRAY_SIZE; i++) val_array[i] = i - 1;

// Display the size of val_array. cout << "Size of val_array = " << val_array.size << endl;

// Display the values of val_array before calling any trigonometry // functions. cout << "The values in val_array:" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << val_array[i] << "   "; cout << endl << endl;

// Initialize rev_valarray that is the reverse of val_array. valarray rev_valarray(ARRAY_SIZE); for (i = 0; i < ARRAY_SIZE; i++) rev_valarray[i] = val_array[ARRAY_SIZE - i - 1];

// Display the size of rev_valarray. cout << "Size of rev_valarray = " << rev_valarray.size << endl;

// Display the values of rev_valarray. cout << "The values in rev_valarray:" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rev_valarray[i] << "   "; cout << endl << endl;

// rvalue_array to hold the return value from calling the trigonometry // functions. valarray rvalue_array;

//    // acos - display the result of rvalue_array //    rvalue_array = acos(val_array); cout << "The result after calling acos:" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

//    // asin - display the result of rvalue_array //    rvalue_array = asin(val_array); cout << "The result after calling asin:" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

//    // atan - display the result of rvalue_array //    rvalue_array = atan(val_array); cout << "The result after calling atan:" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

//    // atan2 - display the result of rvalue_array //

// This template function returns an object of class valarray<T>, // each of whose elements at I is the arctangent of x[I] / y[I]. rvalue_array = atan2(val_array, rev_valarray); cout << "The result after calling atan2(val_array, rev_valarray):" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

// This template function stores in element I the arctangent of   // x[I] / y.    rvalue_array = atan2(val_array, 3.1416); cout << "The result after calling atan2(val_array, 3.1416):" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

// This template function stores in element I the arctangent of   // x / y[I]. rvalue_array = atan2(3.1416, val_array); cout << "The result after calling atan2(3.1416, val_array):" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

//    // cos - display the result of rvalue_array //    rvalue_array = cos(val_array); cout << "The result after calling cos:" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

//    // cosh - display the result of rvalue_array //    rvalue_array = cosh(val_array); cout << "The result after calling cosh:" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

//    // sin - display the result of val_array //    rvalue_array = sin(val_array); cout << "The result after calling sin:" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

//    // sinh - display the result of val_array //    rvalue_array = sinh(val_array); cout << "The result after calling sinh:" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

//    // tan - display the result of val_array //    rvalue_array = tan(val_array); cout << "The result after calling tan:" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

//    // tanh - display the result of val_array //    rvalue_array = tanh(val_array); cout << "The result after calling tanh:" << endl; for (i = 0; i < ARRAY_SIZE; i++) cout << rvalue_array[i] << "    "; cout << endl << endl;

}

Program Output
Size of val_array = 3 The values in val_array: -1   0    1

Size of rev_valarray = 3 The values in rev_valarray: 1   0    -1

The result after calling acos: 3.14159    1.5708     0

The result after calling asin: -1.5708    0     1.5708

The result after calling atan: -0.785398    0     0.785398

The result after calling atan2(val_array, rev_valarray): -0.785398    0     2.35619

The result after calling atan2(val_array, 3.1416): -0.308168    0     0.308168

The result after calling atan2(3.1416, val_array): 1.87896    1.5708     1.26263

The result after calling cos: 0.540302    1     0.540302

The result after calling cosh: 1.54308    1     1.54308

The result after calling sin: -0.841471    0     0.841471

The result after calling sinh: -1.1752    0     1.1752

The result after calling tan: -1.55741    0     1.55741

The result after calling tanh: -0.761594    0     0.761594

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