abs
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的绝对值。
template <class Type>
valarray<Type> abs(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的绝对值。
示例
// valarray_abs.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
int main( )
{
using namespace std;
int i;
valarray<int> va1 ( 9 ), va2 ( 9 );
for ( i = 0 ; i < 4 ; i++ )
va1 [ i ] = -i;
for ( i = 4 ; i < 9 ; i++ )
va1 [ i ] = i;
cout << "The initial valarray is: ";
for (i = 0 ; i < 9 ; i++ )
cout << va1 [ i ] << " ";
cout << "." << endl;
va2 = abs ( va1 );
cout << "The absolute value of the initial valarray is: ";
for (i = 0 ; i < 9 ; i++ )
cout << va2 [ i ] << " ";
cout << "." << endl;
}
The initial valarray is: 0 -1 -2 -3 4 5 6 7 8 .
The absolute value of the initial valarray is: 0 1 2 3 4 5 6 7 8 .
acos
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的反余弦值。
template <class Type>
valarray<Type> acos(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的反余弦值。
备注
返回的元素以弧度为单位。
返回值是 0 和 +pi 之间的主值，它与余弦值输入保持一致。
示例
// valarray_acos.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;
valarray<double> va1 ( 9 );
for ( i = 0 ; i < 9 ; i++ )
va1 [ i ] = 0.25 * i - 1;
valarray<double> va2 ( 9 );
cout << "The initial valarray is:";
for (i = 0 ; i < 9 ; i++ )
cout << " " << va1 [ i ];
cout << endl;
va2 = acos ( va1 );
cout << "The arccosine of the initial valarray is:\n";
for (i = 0 ; i < 9 ; i++ )
cout << setw(10) << va2 [ i ]
<< " radians, which is "
<< setw(11) << (180/pi) * va2 [ i ]
<< " degrees" << endl;
}
The initial valarray is: -1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1
The arccosine of the initial valarray is:
3.14159 radians, which is 180 degrees
2.41886 radians, which is 138.59 degrees
2.0944 radians, which is 120 degrees
1.82348 radians, which is 104.478 degrees
1.5708 radians, which is 90 degrees
1.31812 radians, which is 75.5225 degrees
1.0472 radians, which is 60 degrees
0.722734 radians, which is 41.4096 degrees
0 radians, which is 0 degrees
asin
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的反正弦值。
template <class Type>
valarray<Type> asin(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的反正弦值。
备注
返回的元素以弧度为单位。
返回值是 +pi/2 和 -pi/2 之间的主值，它与正弦值输入保持一致。
示例
// valarray_asin.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;
valarray<double> va1 ( 9 );
for ( i = 0 ; i < 9 ; i++ )
va1 [ i ] = 0.25 * i - 1;
valarray<double> va2 ( 9 );
cout << "The initial valarray is:";
for (i = 0 ; i < 9 ; i++ )
cout << " " << va1 [ i ];
cout << endl;
va2 = asin ( va1 );
cout << "The arcsine of the initial valarray is:\n";
for (i = 0 ; i < 9 ; i++ )
cout << setw(10) << va2 [ i ]
<< " radians, which is "
<< setw(11) << (180/pi) * va2 [ i ]
<< " degrees" << endl;
}
The initial valarray is: -1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1
The arcsine of the initial valarray is:
-1.5708 radians, which is -90 degrees
-0.848062 radians, which is -48.5904 degrees
-0.523599 radians, which is -30 degrees
-0.25268 radians, which is -14.4775 degrees
0 radians, which is 0 degrees
0.25268 radians, which is 14.4775 degrees
0.523599 radians, which is 30 degrees
0.848062 radians, which is 48.5904 degrees
1.5708 radians, which is 90 degrees
atan
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的反正切主值。
template <class Type>
valarray<Type> atan(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的反正切值。
备注
返回的元素以弧度为单位。
返回值是 +pi/2 和 -pi/2 之间的主值，它与正切值输入保持一致。
示例
// valarray_atan.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;
valarray<double> va1 ( 9 );
va1 [ 0 ] = -100;
for ( i = 1 ; i < 8 ; i++ )
va1 [ i ] = 5 * ( 0.25 * i - 1 );
va1 [ 8 ] = 100;
valarray<double> va2 ( 9 );
cout << "The initial valarray is: ";
for ( i = 0 ; i < 9 ; i++ )
cout << va1 [ i ] << " ";
cout << "." << endl;
va2 = atan ( va1 );
cout << "The arcsine of the initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << setw(10) << va2 [ i ]
<< " radians, which is "
<< setw(11) << (180/pi) * va2 [ i ]
<< " degrees" << endl;
cout << endl;
}
The initial valarray is: -100 -3.75 -2.5 -1.25 0 1.25 2.5 3.75 100 .
The arcsine of the initial valarray is:
-1.5608 radians, which is -89.4271 degrees
-1.31019 radians, which is -75.0686 degrees
-1.19029 radians, which is -68.1986 degrees
-0.896055 radians, which is -51.3402 degrees
0 radians, which is 0 degrees
0.896055 radians, which is 51.3402 degrees
1.19029 radians, which is 68.1986 degrees
1.31019 radians, which is 75.0686 degrees
1.5608 radians, which is 89.4271 degrees
atan2
返回的 valarrays 的元素等于由 valarray 常量和元素的组合指定的笛卡尔组件的反正切值。
template <class Type>
valarray<Type> atan2(const valarray<Type>& left, const valarray<Type>& right);
template <class Type>
valarray<Type> atan2(const valarray<Type> left, const Type& right);
template <class Type>
valarray<Type> atan2(const Type& left, const valarray<Type>& right);
参数
left
常量数值数据类型或输入 valarray，它的元素为反正切值参数的 y 轴提供值。
right
常量数值数据类型或输入 valarray，它的元素为反正切值参数的 x 轴提供值。
返回值
一个 valarray，它的元素 I 等于以下项的反正切值：
第一个模板函数为
left[ I ] / _Right [ I ]。第二个模板函数为
left[ I ] /right。第三个模板函数为
left/right[ I ]。
备注
返回的元素以弧度为单位。
此函数可保留参数中组件符号的相关信息（标准正切函数可能会丢失此信息），此象限信息可为返回值分配 +pi 和 -pi 之间的唯一角度值。
如果 left 和 right 具有不同元素数，则结果不可确定。
示例
// valarray_atan2.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;
valarray<double> va1y ( 1 , 4 ), va1x ( 1 , 4 );
va1x [ 1 ] = -1;
va1x [ 2 ] = -1;
va1y [ 2 ] = -1;
va1y [ 3 ] = -1;
valarray<double> va2 ( 4 );
cout << "The initial valarray for the x coordinate is: ( ";
for ( i = 0 ; i < 4 ; i++ )
cout << va1x [ i ] << " ";
cout << ")." << endl;
cout << "The initial valarray for the y coordinate is: ( ";
for ( i = 0 ; i < 4 ; i++ )
cout << va1y [ i ] << " ";
cout << ")." << endl;
va2 = atan2 ( va1y , va1x );
cout << "The atan2 ( y / x ) of the initial valarrays is:\n";
for ( i = 0 ; i < 4 ; i++ )
cout << setw( 10 ) << va2 [ i ]
<< " radians, which is "
<< setw( 11 ) << ( 180/pi ) * va2 [ i ]
<< "degrees" << endl;
cout << endl;
}
The initial valarray for the x coordinate is: ( 1 -1 -1 1 ).
The initial valarray for the y coordinate is: ( 1 1 -1 -1 ).
The atan2 ( y / x ) of the initial valarrays is:
0.785398 radians, which is 45degrees
2.35619 radians, which is 135degrees
-2.35619 radians, which is -135degrees
-0.785398 radians, which is -45degrees
begin
template <class T> unspecified 1 begin(valarray<T>& v);
template <class T> unspecified 2 begin(const valarray<T>& v);
cos
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的余弦值。
template <class Type>
valarray<Type> cos(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的绝对值。
示例
// valarray_cos.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;
valarray<double> va1 ( 9 );
for ( i = 0 ; i < 9 ; i++ )
va1 [ i ] = ( pi ) * ( 0.25 * i - 1 );
valarray<double> va2 ( 9 );
cout << "The initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << setw( 10 ) << va1 [ i ]
<< " radians, which is "
<< setw( 5 ) << ( 180/pi ) * va1 [ i ]
<< " degrees" << endl;
cout << endl;
va2 = cos ( va1 );
cout << "The cosine of the initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << va2 [ i ] << endl;
}
The initial valarray is:
-3.14159 radians, which is -180 degrees
-2.35619 radians, which is -135 degrees
-1.5708 radians, which is -90 degrees
-0.785398 radians, which is -45 degrees
0 radians, which is 0 degrees
0.785398 radians, which is 45 degrees
1.5708 radians, which is 90 degrees
2.35619 radians, which is 135 degrees
3.14159 radians, which is 180 degrees
The cosine of the initial valarray is:
-1
-0.707107
-1.03412e-013
0.707107
1
0.707107
-1.03412e-013
-0.707107
-1
cosh
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的双曲余弦值。
template <class Type>
valarray<Type> cosh(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的双曲余弦值。
注解
定义指数函数的双曲余弦值的标识：
cosh ( z ) = ( exp ( z ) + exp ( - z ) ) / 2
示例
// valarray_cosh.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;
valarray<double> va1 ( 9 );
for ( i = 0 ; i < 9 ; i++ )
va1 [ i ] = pi * ( 0.25 * i - 1 );
valarray<double> va2 ( 9 );
cout << "The initial valarray is:\n";
for (i = 0 ; i < 9 ; i++ )
cout << setw( 10 ) << va1 [ i ]
<< " radians, which is "
<< setw( 5 ) << ( 180/pi ) * va1 [ i ]
<< " degrees" << endl;
cout << endl;
va2 = cosh ( va1 );
cout << "The hyperbolic cosine of the initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << va2 [ i ] << endl;
}
The initial valarray is:
-3.14159 radians, which is -180 degrees
-2.35619 radians, which is -135 degrees
-1.5708 radians, which is -90 degrees
-0.785398 radians, which is -45 degrees
0 radians, which is 0 degrees
0.785398 radians, which is 45 degrees
1.5708 radians, which is 90 degrees
2.35619 radians, which is 135 degrees
3.14159 radians, which is 180 degrees
The hyperbolic cosine of the initial valarray is:
11.592
5.32275
2.50918
1.32461
1
1.32461
2.50918
5.32275
11.592
end
template <class T> unspecified 1 end(valarray<T>& v);
template <class T> unspecified 2 end(const valarray<T>& v);
exp
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的自然指数。
template <class Type>
valarray<Type> exp(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的自然指数值。
示例
// valarray_exp.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
int i;
valarray<double> va1 ( 9 );
for ( i = 0 ; i < 9 ; i++ )
va1 [ i ] = 10 * ( 0.25 * i - 1 );
valarray<double> va2 ( 9 );
cout << "Initial valarray:";
for ( i = 0 ; i < 9 ; i++ )
cout << " " << va1 [ i ];
cout << endl;
va2 = exp ( va1 );
cout << "The natural exponential of the initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << va2 [ i ] << endl;
}
Initial valarray: -10 -7.5 -5 -2.5 0 2.5 5 7.5 10
The natural exponential of the initial valarray is:
4.53999e-005
0.000553084
0.00673795
0.082085
1
12.1825
148.413
1808.04
22026.5
log
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的自然对数。
template <class Type>
valarray<Type> log(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的绝对值。
示例
// valarray_log.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
int i;
valarray<double> va1 ( 9 );
for (i = 0 ; i < 9 ; i++ )
va1 [ i ] = 10 * i;
valarray<double> va2 ( 9 );
cout << "Initial valarray:";
for ( i = 0 ; i < 9 ; i++ )
cout << " " << va1 [ i ];
cout << endl;
va2 = log ( va1 );
cout << "The natural logarithm of the initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << va2 [ i ] << endl;
}
Initial valarray: 0 10 20 30 40 50 60 70 80
The natural logarithm of the initial valarray is:
-inf
2.30259
2.99573
3.4012
3.68888
3.91202
4.09434
4.2485
4.38203
log10
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的以 10 为底的对数或常用对数。
template <class Type>
valarray<Type> log10(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的常用对数值。
示例
// valarray_log10.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
int i;
valarray<double> va1 ( 11 );
for ( i = 0 ; i < 11 ; i++ )
va1 [ i ] = 10 * i;
valarray<double> va2 ( 9 );
cout << "Initial valarray:";
for (i = 0 ; i < 11 ; i++ )
cout << " " << va1 [ i ];
cout << endl;
va2 = log10 ( va1 );
cout << "The common logarithm of the initial valarray is:\n";
for (i = 0 ; i < 11 ; i++ )
cout << va2 [ i ] << endl;
}
Initial valarray: 0 10 20 30 40 50 60 70 80 90 100
The common logarithm of the initial valarray is:
-inf
1
1.30103
1.47712
1.60206
1.69897
1.77815
1.8451
1.90309
1.95424
2
pow
对输入 valarray 的元素和常数进行操作，返回的 valarray 的元素等于由输入 valarray 的元素所指定的基数，或者等于具有一定指数的常数所指定的基数，该指数由输入 valarray 的元素或常数指定。
template <class Type>
valarray<Type>
pow(
const valarray<Type>& left,
const valarray<Type>& right);
template <class Type>
valarray<Type>
pow(
const valarray<Type>& left,
const Type& right);
template <class Type>
valarray<Type>
pow(
const Type& left,
const valarray<Type>& right);
参数
left
输入 valarray，它的元素为每个要指数化的元素提供基数。
right
输入 valarray，它的元素为每个要指数化的元素提供幂。
返回值
一个 valarray，它的元素 I 等于：
对于第一个模板函数，由
left[ I ] 提升至幂right[ I ]。对于第二个模板函数，由
left[ I ] 提升至幂right。对于第三个模板函数，由
left提升至幂right[ I ]。
注解
如果 left 和 right 具有不同元素数，则结果不可确定。
示例
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;
valarray<double> vabase ( 6 );
for ( i = 0 ; i < 6 ; i++ )
vabase [ i ] = i/2;
valarray<double> vaexp ( 6 );
for ( i = 0 ; i < 6 ; i++ )
vaexp [ i ] = 2 * i;
valarray<double> va2 ( 6 );
cout << "The initial valarray for the base is: ( ";
for ( i = 0 ; i < 6 ; i++ )
cout << vabase [ i ] << " ";
cout << ")." << endl;
cout << "The initial valarray for the exponent is: ( ";
for ( i = 0 ; i < 6 ; i++ )
cout << vaexp[ i ] << " ";
cout << ")." << endl;
va2 = pow ( vabase , vaexp );
cout << "The power of (n/2) * exp (2n) for n = 0 to n = 5 is: \n";
for ( i = 0 ; i < 6 ; i++ )
cout << "n = " << i << "\tgives " << va2 [ i ] << endl;
}
The initial valarray for the base is: ( 0 0 1 1 2 2 ).
The initial valarray for the exponent is: ( 0 2 4 6 8 10 ).
The power of (n/2) * exp (2n) for n = 0 to n = 5 is:
n = 0 gives 1
n = 1 gives 0
n = 2 gives 1
n = 3 gives 1
n = 4 gives 256
n = 5 gives 1024
sin
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的正弦值。
template <class Type>
valarray<Type> sin(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的正弦值。
示例
// valarray_sin.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;
valarray<double> va1 ( 9 );
for ( i = 0 ; i < 9 ; i++ )
va1 [ i ] = pi * ( 0.25 * i - 1 );
valarray<double> va2 ( 9 );
cout << "The initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << setw(10) << va1 [ i ]
<< " radians, which is "
<< setw(5) << ( 180/pi ) * va1 [ i ]
<< " degrees" << endl;
cout << endl;
va2 = sin ( va1 );
cout << "The sine of the initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << va2 [ i ] << endl;
}
The initial valarray is:
-3.14159 radians, which is -180 degrees
-2.35619 radians, which is -135 degrees
-1.5708 radians, which is -90 degrees
-0.785398 radians, which is -45 degrees
0 radians, which is 0 degrees
0.785398 radians, which is 45 degrees
1.5708 radians, which is 90 degrees
2.35619 radians, which is 135 degrees
3.14159 radians, which is 180 degrees
The sine of the initial valarray is:
2.06823e-013
-0.707107
-1
-0.707107
0
0.707107
1
0.707107
-2.06823e-013
sinh
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的双曲正弦值。
template <class Type>
valarray<Type> sinh(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的双曲正弦值。
备注
定义指数函数的双曲正弦值的标识：
sinh ( z ) = ( exp ( z ) - exp ( - z ) ) / 2
示例
// valarray_sinh.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;
valarray<double> va1 ( 9 );
for (i = 0 ; i < 9 ; i++ )
va1 [ i ] = pi * ( 0.25 * i - 1 );
valarray<double> va2 ( 9 );
cout << "The initial valarray is:\n";
for (i = 0 ; i < 9 ; i++ )
cout << setw( 10 ) << va1 [ i ]
<< " radians, which is "
<< setw( 5 ) << ( 180/pi ) * va1 [ i ]
<< " degrees" << endl;
cout << endl;
va2 = sinh ( va1 );
cout << "The hyperbolic sine of the initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << va2 [ i ] << endl;
}
The initial valarray is:
-3.14159 radians, which is -180 degrees
-2.35619 radians, which is -135 degrees
-1.5708 radians, which is -90 degrees
-0.785398 radians, which is -45 degrees
0 radians, which is 0 degrees
0.785398 radians, which is 45 degrees
1.5708 radians, which is 90 degrees
2.35619 radians, which is 135 degrees
3.14159 radians, which is 180 degrees
The hyperbolic sine of the initial valarray is:
-11.5487
-5.22797
-2.3013
-0.868671
0
0.868671
2.3013
5.22797
11.5487
sqrt
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的平方根。
template <class Type>
valarray<Type> sqrt(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的平方根。
示例
// valarray_sqrt.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <cmath>
int main( )
{
using namespace std;
int i;
valarray<double> va1 ( 6 );
for ( i = 0 ; i < 5 ; i++ )
va1 [ i ] = i * i;
cout << "The initial valarray is: ( ";
for ( i = 0 ; i < 5 ; i++ )
cout << va1 [ i ] << " ";
cout << ")." << endl;
valarray<double> va2 = sqrt ( va1 );
cout << "The square root of the initial valarray is: ( ";
for ( i = 0 ; i < 5 ; i++ )
cout << va2 [ i ] << " ";
cout << ")." << endl;
}
The initial valarray is: ( 0 1 4 9 16 ).
The square root of the initial valarray is: ( 0 1 2 3 4 ).
swap
交换两个 valarray 的元素。
template <class Type>
void swap(
valarray<Type>& left,
valarray<Type>& right);
参数
left
一个 valarray 类型的对象。
right
一个 valarray 类型的对象。
备注
该模板函数执行 left.swap(right)。
tan
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的正切值。
template <class Type>
valarray<Type> tan(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的正切值。
示例
// valarray_tan.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;
valarray<double> va1 ( 9 );
for ( i = 0 ; i < 9 ; i++ )
va1 [ i ] = ( pi/2 ) * ( 0.25 * i - 1 );
valarray<double> va2 ( 9 );
cout << "The initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << setw( 10 ) << va1 [ i ]
<< " radians, which is "
<< setw( 5 ) << ( 180/pi ) * va1 [ i ]
<< " degrees" << endl;
cout << endl;
va2 = tan ( va1 );
cout << "The tangent of the initial valarray is:\n ";
for ( i = 0 ; i < 9 ; i++ )
cout << va2 [ i ] << endl;
}
The initial valarray is:
-1.5708 radians, which is -90 degrees
-1.1781 radians, which is -67.5 degrees
-0.785398 radians, which is -45 degrees
-0.392699 radians, which is -22.5 degrees
0 radians, which is 0 degrees
0.392699 radians, which is 22.5 degrees
0.785398 radians, which is 45 degrees
1.1781 radians, which is 67.5 degrees
1.5708 radians, which is 90 degrees
The tangent of the initial valarray is:
9.6701e+012
-2.41421
-1
-0.414214
0
0.414214
1
2.41421
-9.6701e+012
tanh
对输入 valarray 的元素进行操作，返回的 valarray 的元素等于输入 valarray 的元素的双曲正切值。
template <class Type>
valarray<Type> tanh(const valarray<Type>& left);
参数
left
输入 valarray，它的元素通过成员函数进行操作。
返回值
一个 valarray，它的元素等于输入 valarray 的元素的双曲余弦值。
注解
定义指数函数的双曲正切值的标识：
tanh ( z ) = sinh ( z ) / cosh ( z ) = ( exp ( z ) - exp ( - z ) ) / ( exp ( z ) + exp ( - z ) )
示例
// valarray_tanh.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>
int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;
valarray<double> va1 ( 9 );
for ( i = 0 ; i < 9 ; i++ )
va1 [ i ] = pi * ( 0.25 * i - 1 );
valarray<double> va2 ( 9 );
cout << "The initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << setw( 10 ) << va1 [ i ]
<< " radians, which is "
<< setw( 5 ) << ( 180/pi ) * va1 [ i ]
<< " degrees" << endl;
cout << endl;
va2 = tanh ( va1 );
cout << "The hyperbolic tangent of the initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << va2 [ i ] << endl;
}
The initial valarray is:
-3.14159 radians, which is -180 degrees
-2.35619 radians, which is -135 degrees
-1.5708 radians, which is -90 degrees
-0.785398 radians, which is -45 degrees
0 radians, which is 0 degrees
0.785398 radians, which is 45 degrees
1.5708 radians, which is 90 degrees
2.35619 radians, which is 135 degrees
3.14159 radians, which is 180 degrees
The hyperbolic tangent of the initial valarray is:
-0.996272
-0.982193
-0.917152
-0.655794
0
0.655794
0.917152
0.982193
0.996272