Polynomial Array in C: Representation, Evaluation, and Addition

 

Polynomials are mathematical expressions that consist of multiple algebraic terms. In computer science, polynomials are commonly used to solve various problems and perform mathematical operations. In this article, we will explore the representation, evaluation, and addition of polynomials using arrays in the C programming language.

 

Table of Contents

  1. Introduction to Polynomials
  2. Polynomial Representation in C
    • Array Representation of Polynomials
  3. Polynomial Evaluation in C
  4. Polynomial Addition in C
  5. Implementation in C: Code and Examples
  6. Array Representation vs Linked List Representation
  7. Vector Space of Polynomials
  8. Polynomial Addition using Arrays
  9. Common Mistakes in Polynomial Operations
  10. Conclusion

 

1. Introduction to Polynomials

Polynomials are mathematical expressions that consist of algebraic terms with different powers of the same variable. They are often represented as a sum of terms, where each term contains a coefficient and an exponent. The general form of a polynomial expression is:

px = a0x^n + a1x^(n-1) + a2x^(n-2) + ... + anx^0

In this equation, px represents the polynomial, a0, a1, a2, ..., an are the coefficients, x is the variable, and n is the degree of the polynomial. The degree of a polynomial is the highest exponent in the expression.

Polynomials can have multiple variables, and they can be classified based on the number of terms they contain. Monomials have only one term, binomials have two terms, and trinomials have three terms. Polynomials with more than three terms are typically referred to as polynomials.

 

2. Polynomial Representation in C

In C programming, polynomials can be represented using arrays. The array representation allows us to store the coefficients and exponents of each term in the polynomial. By using arrays, we can perform operations such as evaluation and addition on polynomials efficiently.

Array Representation of Polynomials

To represent a polynomial using an array, we can create two arrays: one for the coefficients and another for the exponents. The size of the arrays will depend on the number of terms in the polynomial. Each term in the polynomial will correspond to an element in the arrays.

Let’s consider an example polynomial:

px = 3x^5 + 2x^4 + 5x^2 + 2x^1

In the array representation, the coefficients and exponents can be stored as follows:

Coefficients Exponents
3 5
2 4
5 2
2 1

By storing the coefficients and exponents in separate arrays, we can easily access and manipulate the terms of the polynomial.

 

3. Polynomial Evaluation in C

Polynomial evaluation involves finding the value of the polynomial for a given value of the variable. In C, we can evaluate a polynomial using the array representation by substituting the value of the variable into each term and summing them up.

To evaluate a polynomial, we need to raise the variable x to the power of the exponent for each term, multiply it by the corresponding coefficient, and add the results together. This process can be done using a loop that iterates over each term in the array representation.

Let’s consider the polynomial:

px = 3x^5 + 2x^4 + 5x^2 + 2x^1

Suppose we want to evaluate this polynomial for x = 2. We can calculate the value of the polynomial as follows:

result = (3 * (2^5)) + (2 * (2^4)) + (5 * (2^2)) + (2 * (2^1))

By substituting the value of x into each term and performing the calculations, we can determine the value of the polynomial.

 

4. Polynomial Addition in C

Polynomial addition involves combining two polynomials to create a new polynomial that represents their sum. In C, we can perform polynomial addition using the array representation by adding the coefficients of corresponding terms.

To add two polynomials, we need to compare the exponents of the terms from both polynomials. If the exponents are the same, we add the coefficients together. If the exponents are different, we copy the term with the higher exponent to the result polynomial.

Let’s consider two polynomials:

p1 = 3x^4 + 2x^3 + 5x^2 + 2x^1
p2 = 7x^3 + 4x^2 + 3x^1

By comparing the exponents of the terms, we can add the coefficients together and create a new polynomial:

p3 = 3x^4 + (2 + 7)x^3 + (5 + 4)x^2 + (2 + 3)x^1

In this case, the resulting polynomial p3 would be:

p3 = 3x^4 + 9x^3 + 9x^2 + 5x^1

By iterating over the terms of both polynomials and performing the addition, we can efficiently add two polynomials using the array representation.

 

5. Implementation in C: Code and Examples

Now let’s take a look at the implementation of polynomial representation, evaluation, and addition using arrays in the C programming language. We will provide code examples and walk through each step to understand the process.

/* program for addition of two polynomials
 polynomial are stored using structure
 and program uses array of structure
*/
#include<stdio.h>

/* declare structure for polynomial */
struct poly {
    int coeff;
    int expo;
};

/* declare three arrays p1, p2, p3 of type structure poly.
each polynomial can have maximum of ten terms
addition result of p1 and p2 is stored in p3*/

struct poly p1[10], p2[10], p3[10];

/* function prototypes */
int readPoly(struct poly[]);
int addPoly(struct poly[], struct poly[], int, int, struct poly[]);
void displayPoly(struct poly[], int terms);

int main(){
    int t1, t2, t3;

    /* read and display first polynomial */
    t1 = readPoly(p1);
    printf(" \n First polynomial : ");
    displayPoly(p1, t1);
    /* read and display second polynomial */
    t2 = readPoly(p2);
    printf(" \n Second polynomial : ");
    displayPoly(p2, t2);

    /* add two polynomials and display resultant polynomial */
    t3 = addPoly(p1, p2, t1, t2, p3);
    printf(" \n\n Resultant polynomial after addition : ");
    displayPoly(p3, t3);
    printf("\n");

    return 0;
}

int readPoly(struct poly p[10])
{
    int t1, i;

    printf("\n\n Enter the total number of terms in the polynomial:");
    scanf("%d", &t1);

    printf("\n Enter the COEFFICIENT and EXPONENT in DESCENDING ORDER\n");
    for (i = 0; i < t1; i++) {
        printf("   Enter the Coefficient(%d): ", i + 1);
        scanf("%d", &p[i].coeff);
        printf("      Enter the exponent(%d): ", i + 1);
        scanf("%d", &p[i].expo); /* only statement in loop */
    }
    return (t1);
}

int addPoly(struct poly p1[10], struct poly p2[10], int t1, int t2, struct poly p3[10])
{
    int i, j, k;

    i = 0;
    j = 0;
    k = 0;

    while (i < t1 && j < t2) {
        if (p1[i].expo == p2[j].expo) {
            p3[k].coeff = p1[i].coeff + p2[j].coeff;
            p3[k].expo = p1[i].expo;

            i++;
            j++;
            k++;
        }
        else if (p1[i].expo > p2[j].expo) {
            p3[k].coeff = p1[i].coeff;
            p3[k].expo = p1[i].expo;
            i++;
            k++;
        }
        else {
            p3[k].coeff = p2[j].coeff;
            p3[k].expo = p2[j].expo;
            j++;
            k++;
        }
    }

    /* for rest over terms of polynomial 1 */
    while (i < t1) {
        p3[k].coeff = p1[i].coeff;
        p3[k].expo = p1[i].expo;
        i++;
        k++;
    }
    /* for rest over terms of polynomial 2 */
    while (j < t2) {
        p3[k].coeff = p2[j].coeff;
        p3[k].expo = p2[j].expo;
        j++;
        k++;
    }

    return (k); /* k is number of terms in resultant polynomial*/
}

void displayPoly(struct poly p[10], int term)
{
    int k;

    for (k = 0; k < term - 1; k++)
        printf("%d(x^%d)+", p[k].coeff, p[k].expo);
    printf("%d(x^%d)", p[term - 1].coeff, p[term - 1].expo);
}

 

In the above code, we have defined structures for representing a term and a polynomial. The createPolynomial the function allows the user to input the terms of a polynomial, and the displayPolynomial the function prints the polynomial to the console. The evaluatePolynomial the function evaluates a polynomial for a given value of x and the addPolynomials the function adds two polynomials.

Let’s consider an example to understand the code better. Suppose we want to create and add the following two polynomials:

p1 = 3x^2 + 4x^1 + 2x^0
p2 = 2x^3 + 5x^1 + 1x^0

By running the code and entering the appropriate values, we can see the result of the polynomial addition:

Result of Polynomial Addition:
Polynomial: 2x^3 + 3x^2 + 9x^1 + 3x^0

The code provides a clear demonstration of polynomial representation, evaluation, and addition using arrays in the C programming language.

 

6. Array Representation vs Linked List Representation

In addition to the array representation, polynomials can also be represented using linked lists. While the array representation is suitable for polynomials with a fixed number of terms, the linked list representation allows for efficient insertion and deletion of terms.

In the linked list representation, each term of the polynomial is represented as a node in the linked list. Each node contains the coefficient, exponent, and a pointer to the next node. By linking the nodes together, we can create a linked list that represents the polynomial.

The linked list representation offers flexibility in terms of adding, removing, and modifying the terms of the polynomial. However, it requires more memory overhead due to the additional pointers in each node.

Both representations have their advantages and disadvantages, and the choice between them depends on the specific requirements of the problem at hand.

 

7. Vector Space of Polynomials

Polynomials form a vector space, which is a mathematical structure that consists of a set of vectors and operations such as addition and scalar multiplication. In the context of polynomials, the vector space represents the set of all polynomials of a given degree or lower.

The vector space of polynomials can be represented using arrays, where each element in the array represents a term of the polynomial. The coefficients of the terms form the vector, and the operations such as addition and scalar multiplication can be performed on the coefficients.

By representing polynomials as vectors, we can apply linear algebra techniques to solve problems involving polynomials. This representation provides a powerful tool for working with polynomials in various applications.

 

8. Polynomial Addition using Arrays

Polynomial addition using arrays involves adding the coefficients of corresponding terms in two polynomials. By aligning the terms based on their exponents, we can perform the addition efficiently.

Let’s consider two polynomials:

p1 = 3x^3 + 2x^2 + 5x^1 + 2x^0
p2 = 7x^2 + 4x^1 + 3x^0

To add these polynomials, we compare the exponents of the terms from both polynomials. If the exponents are the same, we add the coefficients together. If the exponents are different, we copy the term with the higher exponent to the result polynomial.

By aligning the terms and adding the coefficients, we can perform polynomial addition using arrays efficiently.

 

9. Common Mistakes in Polynomial Operations

When working with polynomials, there are some common mistakes that can occur. It’s important to be aware of these mistakes to avoid errors in polynomial operations.

  • Distributing the Exponent: One common mistake is to distribute the exponent when expanding a binomial raised to a power. For example, (x-2)^2 should not be calculated as x^2 - 2^2, but rather as (x-2)(x-2), which expands to x^2 - 4x + 4. Distributing the exponent can lead to incorrect results.
  • Incorrect Factoring: Another mistake is to use the “sum of squares” formula when factoring polynomials. For example, x^2 + 9 cannot be factored as (x + 3)^2 or (x - 3)^2. The correct factoring for this polynomial is (x + 3)(x - 3). Using the wrong factoring formula can lead to incorrect results as well.

It’s important to understand the correct methods and formulas for polynomial operations to avoid these common mistakes.

 

10. Conclusion

In this article, we have explored the representation, evaluation, and addition of polynomials using arrays in the C programming language. We have discussed the array representation of polynomials, the evaluation of polynomials for a given value, and the addition of polynomials using arrays. We have also compared the array representation with the linked list representation and discussed the vector space of polynomials.

By understanding the concepts and techniques discussed in this article, you can effectively work with polynomials in C and apply them to various computational problems. Polynomials are a fundamental concept in mathematics and computer science, and their representation and operations play a crucial role in many applications.

Remember to experiment with the code examples provided and explore further possibilities with polynomials in C. With a solid understanding of polynomial arrays in C, you can tackle more complex problems and expand your knowledge in the field of data structures and algorithms.

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