<h2>Overview</h2>

The **`nexttowardf()`** calculates the next value after a number `x` in the direction of another number `y` in a precise manner. `nexttowardf()` is similar to the `nextafter()` function. 

`nexttowardf()` is defined in the `<math.h>` library, so you must include the `<math.h>` library at the beginning of your program as shown below:

```C
#include<math.h>
```
The `nexttowardf()` function is defined in the `<math.h>` header files as shown below:

```C
float nexttowardf( float x, long double y );
```

<h2>Parameters</h2>

The `nexttowardf()` function takes two parameters, `x` and `y`, of type `float` and `long double` respectively. 

<h2>Return value</h2>

`x` is defined as 'from' and `y` as 'to' because the function returns the next floating-point number from `x` and in the direction of `y`.

Moreover, the return values vary for some distinct values of `x` and `y`:

1. If $x=y$, then the `nexttowardf()` function returns $y$.
2. If either `x` or `y` are `Not a Number (NaN)`, then the function returns `NaN`.
3. If the resultant floating point underflows, the return value would still be correct.

The return value never depends on the current rounding mode in any case. 

<h2>Error handling</h2>

The following errors can be returned if the `nexttowardf()` function is not executed successfully:
1. In the case of an overflow, the `HUGE_VALF` macro is returned.
2. If the return value is infinity despite a finite `x` value, the `FE_INEXACT` and `FE_OVERFLOW` errors are returned due to overflow. 
3. If the result is not normal or zero, this indicates an underflow. In this case, the `FE_INEXACT` and `FE_UNDERFLOW` flags are raised. 

<h2>Example</h2>

Below is an example of how you can use the `nexttowardf()` function. It calculates the next floating-point number after $0$ in the direction of $1$ (positive numbers).

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

int main() {
    float from = 0;
    long double to = 1;

    float result = nexttowardf(from, to);
    printf("the next number from 0 in the direction of 1 is: %f\n", result);
    
    return 0;
}

gcc compiler

gcc.tar.gz

What is nexttowardf in C?

The nexttowardf() function computes the next floating-point value after x towards y with error handling for overflow and underflow situations.