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

• 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);

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

1    0    -1

3.14159     1.5708     0

-1.5708     0     1.5708

-0.785398     0     0.785398

-0.785398     0     2.35619

-0.308168     0     0.308168

1.87896     1.5708     1.26263

0.540302     1     0.540302

1.54308     1     1.54308

-0.841471     0     0.841471

-1.1752     0     1.1752

-1.55741     0     1.55741

-0.761594     0     0.761594

REFERENCES

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