polynomial addition

polynomial.c

@@ -0,0 +1,148 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define MAX_TERMS 100
+
+typedef struct {
+    float coef;
+    int expon;
+} polynomial;
+
+polynomial terms[MAX_TERMS];
+int avail = 0;
+
+int COMPARE(int a, int b)
+{
+    if (a < b)
+        return -1;
+    if (a == b)
+        return 0;
+    else
+        return 1;
+}
+
+void attach(float coefficient, int exponent)
+{
+    if (avail >= MAX_TERMS) {
+        fprintf(stderr, "Too many terms in the polynomial\n");
+        exit(1);
+    }
+    terms[avail].coef = coefficient;
+    terms[avail++].expon = exponent;
+}
+
+/* sort terms[start..finish] in DESCENDING order of exponent */
+void sort_poly(int start, int finish)
+{
+    int i, j;
+    polynomial temp;
+    for (i = start; i < finish; i++) {
+        for (j = i + 1; j <= finish; j++) {
+            if (terms[i].expon < terms[j].expon) {
+                temp = terms[i];
+                terms[i] = terms[j];
+                terms[j] = temp;
+            }
+        }
+    }
+}
+
+void padd(int starta, int finisha, int startb, int finishb,
+          int *startd, int *finishd)
+{
+    float coefficient;
+    *startd = avail;
+
+    while (starta <= finisha && startb <= finishb) {
+        switch (COMPARE(terms[starta].expon, terms[startb].expon)) {
+            case -1:
+                attach(terms[startb].coef, terms[startb].expon);
+                startb++;
+                break;
+            case 0:
+                coefficient = terms[starta].coef + terms[startb].coef;
+                if (coefficient) {
+                    attach(coefficient, terms[starta].expon);
+                }
+                starta++;
+                startb++;
+                break;
+            case 1:
+                attach(terms[starta].coef, terms[starta].expon);
+                starta++;
+                break;
+        }
+    }
+
+    for (; starta <= finisha; starta++)
+        attach(terms[starta].coef, terms[starta].expon);
+    for (; startb <= finishb; startb++)
+        attach(terms[startb].coef, terms[startb].expon);
+
+    *finishd = avail - 1;
+}
+
+int main(void)
+{
+    int i, j, ae, be, nA, nB, sa, sb, fa, fb, sc, fc = 0;
+    int *sd, *fd;
+    float ac, bc;
+
+    printf("Enter number of terms in Polynomial A: ");
+    scanf("%d", &nA);
+
+    printf("Enter terms for A (coefficient exponent), in ANY order:\n");
+    for (i = 0; i < nA; i++) {
+        printf("A[%d]: ", i + 1);
+        scanf("%f%d", &ac, &ae);
+        attach(ac, ae);
+    }
+
+    fa = avail - 1;   // A ends here
+
+    sb = avail;
+    printf("\nEnter number of terms in Polynomial B: ");
+    scanf("%d", &nB);
+
+    printf("Enter terms for B (coefficient exponent), in ANY order:\n");
+    for (i = 0; i < nB; i++) {
+        printf("B[%d]: ", i + 1);
+        scanf("%f%d", &bc, &be);
+        attach(bc, be);
+    }
+    fb = avail - 1;   // B ends here
+
+    // sort A and B by exponent so padd works correctly
+    sort_poly(0, fa);
+    sort_poly(sb, fb);
+
+    printf("\n-----------------------------------------\n");
+    printf("Polynomial A: ");
+    for (i = 0; i < nA; i++) {
+        printf("%.2fx^%d", terms[i].coef, terms[i].expon);
+        if (i < nA - 1) printf(" + ");
+    }
+
+    printf("\nPolynomial B: ");
+    for (i = sb; i <= fb; i++) {
+        printf("%.2fx^%d", terms[i].coef, terms[i].expon);
+        if (i < fb) printf(" + ");
+    }
+    printf("\n-----------------------------------------\n");
+
+    sa = 0;
+    sc = avail;
+    sd = &sc;
+    fd = &fc;
+
+    padd(sa, fa, sb, fb, sd, fd);
+
+    printf("Result (A + B): ");
+    for (j = sc; j <= fc; j++) {
+        printf("%.2fx^%d", terms[j].coef, terms[j].expon);
+        if (j < fc) printf(" + ");
+    }
+    printf("\n-----------------------------------------\n");
+
+    return 0;
+}