Usage

`javascript
var compile = require( '@stdlib/math-base-tools-evalrational-compile-c' );
`

#### compile( P, Q )

Compiles a C function for evaluating a [rational function][@stdlib/math/base/tools/evalrational] having coefficients P and Q.

`javascript
var P = [ 3.0, 2.0, 1.0 ];
var Q = [ -1.0, -2.0, -3.0 ];

var str = compile( P, Q );
// returns
`

The function supports the following options:

- dtype: input argument floating-point data type (e.g., double or float). Default: 'double'.
- name: function name. Default: 'evalpoly'.

In the example above, the output string would correspond to the following function:

`c
/**
* Evaluates a rational function (i.e., the ratio of two polynomials described by the coefficients stored in \\(P\\) and \\(Q\\)).
*
* ## Notes
*
* - Coefficients should be sorted in ascending degree.
* - The implementation uses [Horner's rule][horners-method] for efficient computation.
*
* [horners-method]: https://en.wikipedia.org/wiki/Horner%27s_method
*
* @param x value at which to evaluate the rational function
* @returns evaluated rational function
*/
static double evalrational( const double x ) {
double ax;
double ix;
double s1;
double s2;
if ( x == 0.0 ) {
return -3.0;
}
if ( x < 0.0 ) {
ax = -x;
} else {
ax = x;
}
if ( ax <= 1.0 ) {
s1 = 3.0 + (x (2.0 + (x 1.0)));
s2 = -1.0 + (x (-2.0 + (x -3.0)));
} else {
ix = 1.0 / x;
s1 = 1.0 + (ix (2.0 + (ix 3.0)));
s2 = -3.0 + (ix (-2.0 + (ix -1.0)));
}
return s1 / s2;
}
`

To generate a function having a custom name and supporting single-precision floating-point numbers, provide the corresponding options.

`javascript
var P = [ 3.0, 2.0, 1.0 ];
var Q = [ -1.0, -2.0, -3.0 ];

var opts = {
'dtype': 'float',
'name': 'rational123'
};
var str = compile( P, Q, opts );
// returns
`

For the previous example, the output string would correspond to the following function:

`c
/**
* Evaluates a rational function (i.e., the ratio of two polynomials described by the coefficients stored in \\(P\\) and \\(Q\\)).
*
* ## Notes
*
* - Coefficients should be sorted in ascending degree.
* - The implementation uses [Horner's rule][horners-method] for efficient computation.
*
* [horners-method]: https://en.wikipedia.org/wiki/Horner%27s_method
*
* @param x value at which to evaluate the rational function
* @returns evaluated rational function
*/
static float rational123( const float x ) {
float ax;
float ix;
float s1;
float s2;
if ( x == 0.0f ) {
return -3.0f;
}
if ( x < 0.0f ) {
ax = -x;
} else {
ax = x;
}
if ( ax <= 1.0f ) {
s1 = 3.0f + (x (2.0f + (x 1.0f)));
s2 = -1.0f + (x (-2.0f + (x -3.0f)));
} else {
ix = 1.0f / x;
s1 = 1.0f + (ix (2.0f + (ix 3.0f)));
s2 = -3.0f + (ix (-2.0f + (ix -1.0f)));
}
return s1 / s2;
}
`