Fdim Function In C

Syntax of fdim:

#include <math.h>

double fdim(double x, double y);

float fdimf(float x, float y);

long double fdiml(long double x, long double y);

Where,

• ✅ fdim(double x, double y)- This function computes the positive difference between two double values x and y.
• ✅ fdimf(float x, float y)- This function computes the positive difference between two float values x and y.
• ✅ fdiml(long double x, long double y)- This function computes the positive difference between two long double values x and y.

Note: In each case, if x > y, the function returns x - y; otherwise, it returns 0.0.

Return Value of fdim

The output from the fdim function is determined by the relationship between its two parameters, x and y. The function behaves as follows:

• ✅ In cases where x is larger than y, the result will be the absolute value of the difference between x and y: x - y.
• ✅ When x is less than or equal to y, the function will yield a value of 0.0.

The return type of the function matches the type of the input parameters:

• ✅ The return type is double for fdim(double x, double y).
• ✅ The return type is float for fdimf(float x, float y).
• ✅ The return type is long double for fdiml(long double x, long double y).

Examples of fdim

Case 1:

x is greater than y

Input: fdim(10.5, 4.2)

Output: 6.3

Case 2:

x is less than or equal to y

Input: fdim(3.1, 5.7)

Output: 0.0

Example 1:

Let's consider a C program to showcase the functionality of the fdim function.

#include <math.h>

#include <stdio.h>



int main()

{

    // declare and initialize variables

    double num1 = 8.7, num2 = 6.4;

    // compute positive difference using fdim() function

    double posDiff = fdim(num1, num2);



    // Print the positive difference

    printf("The positive difference between %.2lf and "

           "%.2lf is: %.2lf\n",

           num1, num2, posDiff);



    return 0;

}

Output:

The positive difference between 8.70 and 6.40 is: 2.30

Example 2:

Let's consider a C code example to showcase the application of the fdim function with different floating-point data types.

#include <math.h>

#include <stdio.h>



int main()

{

    // declare and initialize variables

    double num1 = 8.5, num2 = 4.3;

    float num3 = 9.6f, num4 = 2.5f;

    long double num5 = 10.7l, num6 = 3.4l;



    // compute positive difference using fdim() for double

    double diff1 = fdim(num1, num2);



    // compute positive difference using fdimf() for float

    float diff2 = fdimf(num3, num4);



    // compute positive difference using fdiml() for long double

    long double diff3 = fdiml(num5, num6);



    // Print the positive differences

    printf("The positive difference between %.2lf and "

           "%.2lf is: %.2lf\n",

           num1, num2, diff1);

    printf("The positive difference between %.2f and %.2f "

           "is: %.2f\n",

           num3, num4, diff2);

    printf("The positive difference between %.2Lf and "

           "%.2Lf is: %.2Lf\n",

           num5, num6, diff3);



    return 0;

}

Output:

The positive difference between 8.50 and 4.30 is: 4.20

The positive difference between 9.60 and 2.50 is: 7.10

The positive difference between 10.70 and 3.40 is: 7.30

Features of fdim

• ✅ Positive Difference Calculation: The principal purpose of fdim intrinsic function is to return the positive difference of two floating-point numbers. When x > y, it returns x - y; otherwise, if x <= y, it returns 0.
• ✅ Support for Different Floating-Point Types: The function is generic for floating point type; raises remainder of 'a' to single precision float, 'b' to double precision double, and 'c' to long double using fdim, fdimf, and fdiml respectively. This makes it possible according to the need of the application in terms of the degree of precision.
• ✅ Mathematical Precision: Again, in computing the positive difference, fdim guarantees the accurate and correct computation to meet numerous mathematical and scientific processes where the negative discrepancies cannot be embraced.
• ✅ Portability: Thus, since fdim is a part of the C Standard Library and declared in <math. h>, it is not sensitive to the platform or compiler that does not conform to the C standard.
• ✅ Error Handling: The function can handle rather specific values of the floating-point type, particularly NaN (Not a Number) and Infinity. If either of the parameters x or y is a NaN, then the operation's result is also NaN. If x and the variable are positive infinity and y is finite, the resulting value is positive infinity.
• ✅ Efficient Implementation: Implemented efficiently inside standard libraries, fdim is used for precise positive difference calculations, and it is designed for the application's required efficiency, sometimes using function creation.

Drawbacks of fdim

• ✅ Limited Use Case: The fdim is a function that only computes the positive difference between two numbers. However, it is less general than the other arithmetic functions because the absolute value cannot be used directly for negative differences and general subtraction.
• ✅ Handling of Special Values: As for NaN and Infinity, fdim deals with them, but the action may be quite unexpected. For example, if one of the inputs is NaN, then the result of the % operator is also NaN, which may sometimes need special checks in the code.
• ✅ Lack of Integer Support: The fdim function is only appropriate for the floating-point numbers alone. It does not include the integer type; hence, any integer is required to be converted or cast into a floating point type before it can be passed to fdim, which may lead to loss of precision or added computational process.
• ✅ Potential for Misuse: The user could misinterpret the function objectives and may use extract when a subtraction would suffice or a subtraction where an extract should be made, and therefore mislead himself.
• ✅ Performance Considerations: Although the function is efficient, it entails an 'if …else..' construction to test for the conditions in which to return the difference or zero. In general, applications where these operations are performed frequently, and even small overhead can add up.
• ✅ Standard Library Dependency: Being a part of the C Standard Library, the fdim function means that including <math. h>. This dependency might not be desirable usually, especially in specific scenarios where the use of libraries needs to be restricted as much as possible.
• ✅ Compiler and Platform Variations: The results and performance of fdim may differ with respect to the compiler and the platform and, as a result, may be inconsistent.

Conclusion:

The fdim function within the C programming language serves a distinct purpose by calculating the positive difference between two floating-point numbers. It is implemented through the <math> header file and outputs the result as an unsigned char, ensuring a non-negative outcome. This functionality is valuable in various scenarios, especially within mathematical and scientific calculations. Additionally, fdim accommodates double, float, and long double data types, catering to varying levels of precision in floating-point operations.

In a broad sense, the fdim function can be viewed as a valuable tool, despite a few minor variations. As previously stated, its primary purpose is to compute positive variances. It does not accommodate integer inputs. Nevertheless, handling unique values like NaN and Infinity may require additional attention, as it relies on the C Standard Library, which may not always be ideal. Moreover, the conditional statements utilized in the function's coding, while versatile and clear, could introduce subtle overhead in performance-critical scenarios.

In summary, it is advantageous to understand the efficiency and inefficiency of utilizing the fdim function. Developers who possess a thorough understanding of this function, including its drawbacks, can write optimized code that provides accurate and favorable solutions when needed.