pi_c

 Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input Detailed_Output Parameters Exceptions Files Particulars Examples Restrictions Literature_References Author_and_Institution Version Index_Entries

#### Procedure

```   SpiceDouble pi_c ( void )

```

#### Abstract

```   Return the value of pi (the ratio of the circumference of
a circle to its diameter).
```

```   None.
```

#### Keywords

```   CONSTANTS

```

#### Brief_I/O

```   The function returns the value of pi.
```

#### Detailed_Input

```   None.
```

#### Detailed_Output

```   The function returns the value of pi (the ratio of a circle's
circumference to its diameter), determined by the ACOS function.
That is,

pi_c = acos ( -1.0 );
```

#### Parameters

```   None.
```

#### Exceptions

```   Error free.
```

#### Files

```   None.
```

#### Particulars

```   The first time the function is referenced, the value is computed
as shown above. The value is saved, and returned directly upon
subsequent reference.
```

#### Examples

```   The code fragment below illustrates the use of pi_c.

/.

p
----------------
1 + e cos(theta)

at evenly spaced values of the polar angle, theta.
./
delta = pi_c() / n

for ( i = 0; i < n, i++ )
{
r[i] = p / (1.0 + ecc * cos( i * delta) );
}
```

#### Restrictions

```   None.
```

#### Literature_References

```   None.
```

#### Author_and_Institution

```   E.D. Wright     (JPL)
W.L. Taber      (JPL)
I.M. Underwood  (JPL)
```

#### Version

```   -CSPICE Version 1.0.0, 08-FEB-1998 (EDW)
```

#### Index_Entries

```   value of pi
```
`Wed Apr  5 17:54:40 2017`