The **`fminl` function** is defined in the `<tgmath.h>` header file in C. It takes in two parameters of type `long double`: `x` and `y`. It then returns the smaller of the two numbers. 

The illustration below shows how the `fminl` function works:

# Declaration

The `fminl` function is defined as follows:

```C
long double fminl( long double x, long double y );
```

# Parameters

The `fminl` function takes two values of the `long double` type as parameters. 

# Return value

The `fminl` function returns the smaller of the two `long double` values.

# Error handling

The `fminl` function returns special values for certain arguments:

| x  | y  | Returned Value |
| - | - | - | 
| valid `long double`  | `NaN` | `x` |
|`NaN` | valid `long double` |`y` |
|`NaN`|`NaN`| `Nan`|

# Example

The following code snippet shows how we can use the `fminl` function:

#include <stdio.h> // include header for printf
#include <tgmath.h> // include header for fminl
 
int main(){

  // setting values for x and y
  long double x = 2.0;
  long double y = 4.0;
  long double result;

  result = fminl(x, y);
  printf("The result is: %Lf", result);  
  return 0;
}

What is fminl in C?

It returns the smaller of two long double values and handles NaN inputs accordingly.

x	y	Returned Value
valid `long double`	`NaN`	`x`
`NaN`	valid `long double`	`y`
`NaN`	`NaN`	`Nan`