Use trigonometry STL functions in Visual C++
The sample code below illustrates how to use the STL acos, asin, atan, atan2, cos, cosh, sin, sinh, tan, tanh functions in Visual C++. The information in this article applies to unmanaged Visual C++ code only.
Original product version: Visual C++
Original KB number: 157950
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 or parameter names in the prototype may not match the version in the header file. Some have been modified to improve readability.
Sample code
This article illustrates the use of STL trigonometry functions through the following 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
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
//////////////////////////////////////////////////////////////////////
#include <iostream> // for i/o functions
#include <valarray> // for valarray
#include <cmath> // for trigonometry functions
#if _MSC_VER > 1020 // if VC++ version is > 4.2
using namespace std; // std c++ libs implemented in std
#endif
#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.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<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.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<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
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