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*AIX Version 4.3 Base Operating System and Extensions Technical Reference, Volume 2*

## sin, sinl, cos, cosl, tan, or tanl Subroutine

### Purpose

Computes the trigonometric functions.

### Libraries

IEEE Math Library (**libm.a**)

or System V Math Library (**libmsaa.a**)

### Syntax

**#include <math.h>**

**double sin (***x***)**
**double ***x***;**

**long double sinl (***x***)**
**long double ***x***;**

**double cos (***x***)**
**double ***x***;**

**long double cosl (***x***)**
**long double ***x***;**

**double tan (***x***)**
**double ***x***;**

**long double tanl (***x***)**
**long double ***x***;**

### Description

The **sin**, **cos**, and **tan** subroutines return the sine, cosine, and tangent, respectively, of their parameters, which are in radians. The **sinl** subroutine, **cosl** subroutine, and **tanl** subroutine return the same values, but these subroutines take and return numbers of the long double data type.

### Parameters

*x* |
Specifies some double-precision floating-point value. For the **sinl**, **cosl**, and **tanl** subroutines, specifies a long double-precision floating-point value. |

*y* |
Specifies some double-precision floating-point value. For the **sinl** subroutine, **cosl** subroutine, and **tanl** subroutine, specifies a long double-precision floating-point value. |

### Error Codes

The **sin**, **sinl**, **cos**, **cosl, tan**, and **tanl **subroutines lose accuracy when passed a large value for the *x* parameter. In the **sin** subroutine, for example, values of *x *that are greater than pi are argument-reduced by first dividing them by the machine value for 2 *` pi `
, and then using the IEEE remainder of this division in place of *x.* Since the machine value of` pi `
can only approximate its infinitely precise value, the remainder of x/(2 * `pi`
) becomes less accurate as *x* becomes larger. Similar loss of accuracy occurs for the **sinl**, **cos**, **cosl**, **tan**, and **tanl **subroutines during argument reduction of large arguments.

**sin,** **cos, ** |
When the *x* parameter is extremely large, these functions return 0 when there would be a complete loss of significance. In this case, a message indicating **TLOSS** error is printed on the standard error output. For less extreme values causing partial loss of significance, a **PLOSS** error is generated but no message is printed. In both cases, the **errno** global variable is set to a **ERANGE **value. |

These error-handling procedures may be changed with the **matherr** subroutine when using the **libmsaa.a **(**-lmsaa**) library.

### Implementation Specifics

These subroutines are part of Base Operating System (BOS) Runtime.

### Related Information

The **matherr** subroutine, **sinh**, **sinhl**, **cosh**, **coshl**, **tanh**, or **tanhl** subroutines.

Subroutines Overview in *AIX Version 4.3 General Programming Concepts: Writing and Debugging Programs*.

128-Bit long double Floating-Point Format in
*AIX Version 4.3 General Programming Concepts: Writing and Debugging Programs*.

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