STL Sample for Trigonometry (sin, cos, tan, etc.) Functions

ID: Q157950

The information in this article applies to:

The Standard C++ Library included with:
- Microsoft Visual C++, 32-bit Edition, version 4.2

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++.

MORE INFORMATION

Required Header

   <valarray>
   <cmath>

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.
////////////////////////////////////////////////////////////////////// 

#include <iostream>                 // for i/o functions
#include <valarray>                 // for valarray
#include <cmath>                    // for trigonometry functions

#define ARRAY_SIZE  3               // array size

void main()

{

    // Initialize val_array to values -1, 0 and 1.
    valarray<double> 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.length() << 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<double> 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.length() << 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<double> 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

REFERENCES

Visual C++ Books On Line: Visual C++ Books:C/C++:Standard C++ Library Reference.

Additional query words: STL STLSample acos, asin, atan, atan2, cos, cosh, sin, sinh, tan, tanh

Keywords          : kbcode STLIss 
Version           : WINNT:4.2;
Platform          : NT WINDOWS
Issue type        : kbhowto

Last Reviewed: October 10, 1997