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Trigonometry Functions
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Trigonometry Functions 

Illustrates how to use trigonometry (sin, cos, tan, and so on) functions in Visual C++.


// 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
   );

NoteNote

The class/parameter names in the prototype do not match the version in the header file. Some have been modified to improve readability.

// trig.cpp
// compile with: /EHsc
// Illustrates the use of STL trigonometry functions.
// Functions:
//  acos, asin, atan, atan2, cos, cosh, sin, sinh, tan, tanh
//////////////////////////////////////////////////////////////////////

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

using namespace std ;

#define ARRAY_SIZE  3               // array size

int main()
{
   // Initialize val_array to values -1, 0 and 1.
   valarray<double> val_array(ARRAY_SIZE);
   int i;
   for (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;
}

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 ]

Header: <valarray>

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