请问如何求余切值?

[livck]

如题，给出代码。谢谢！

[oilking_zhh]

余弦/正弦

[快乐鹦鹉]

float fctg = cos(x)/sin(x);

[Kudeet]

不是有tan/atan函数直接计算吗

[Kudeet]

* ATAN.C: This program calculates
* the arctangent of 1 and -1.
*/

#include <math.h>
#include <stdio.h>
#include <errno.h>

void main( void )
{
double x1, x2, y;

printf( "Enter a real number: " );
scanf( "%lf", &x1 );
y = atan( x1 );
printf( "Arctangent of %f: %f\n", x1, y );
printf( "Enter a second real number: " );
scanf( "%lf", &x2 );
y = atan2( x1, x2 );
printf( "Arctangent of %f / %f: %f\n", x1, x2, y );
}


Output

Enter a real number: -862.42
Arctangent of -862.420000: -1.569637
Enter a second real number: 78.5149
Arctangent of -862.420000 / 78.514900: -1.480006

[菜牛]

Standard C++ Library Reference

<valarray> Members


Functions

abs Operates on the elements of an input valarray, returning a valarray whose elements are equal to the absolute value of the elements of the input valarray.
acos Operates on the elements of an input valarray, returning a valarray whose elements are equal to the arccosine of the elements of the input valarray.
asin Operates on the elements of an input valarray, returning a valarray whose elements are equal to the arcsine of the elements of the input valarray.
atan Operates on the elements of an input valarray, returning a valarray whose elements are equal to the principal value of the arctangent of the elements of the input valarray.
atan2 Returns a valarray whose elements are equal to the arctangent of the Cartesian components specified by a combination of constants and elements of valarrays.
cos Operates on the elements of an input valarray, returning a valarray whose elements are equal to the cosine of the elements of the input valarray.
cosh Operates on the elements of an input valarray, returning a valarray whose elements are equal to the hyperbolic cosine of the elements of the input valarray.
exp Operates on the elements of an input valarray, returning a valarray whose elements are equal to the natural exponential of the elements of the input valarray.
log Operates on the elements of an input valarray, returning a valarray whose elements are equal to the natural logarithm of the elements of the input valarray.
log10 Operates on the elements of an input valarray, returning a valarray whose elements are equal to the base 10 or common logarithm of the elements of the input valarray.
pow Operates on the elements of input valarrays and constants, returning a valarray whose elements are equal to a base specified either by the elements of an input valarray or a constant raised to an exponent specified either by the elements of an input valarray or a constant.
sin Operates on the elements of an input valarray, returning a valarray whose elements are equal to the sine of the elements of the input valarray.
sinh Operates on the elements of an input valarray, returning a valarray whose elements are equal to the hyperbolic sine of the elements of the input valarray.
sqrt Operates on the elements of an input valarray, returning a valarray whose elements are equal to the square root of the elements of the input valarray.
tan Operates on the elements of an input valarray, returning a valarray whose elements are equal to the tangent of the elements of the input valarray.
tanh Operates on the elements of an input valarray, returning a valarray whose elements are equal to the hyperbolic tangent of the elements of the input valarray.

[快乐鹦鹉]

兄弟，余切和atan可是两回事啊