dm1sh/polynomial_interpolation
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Updated (shortened) Newton polynomial printing, added simplified polynomial printing

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Dmitriy Shishkov 2021-10-31 03:28:40 +03:00
parent 95a1c4cb81
commit 9155c87b65
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GPG Key ID: 14358F96FCDD8060
2 changed files with 80 additions and 8 deletions
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82
main.c
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@ -1,5 +1,12 @@
#include "./polynominal_interpolation.h"
/* Utils */
double fabs(double x)
{
return x > 0 ? x : -x;
}
/*
Newton interpolation polynomial
*/
@ -100,15 +107,42 @@ double mult_by_indexes(double *arr, unsigned int *indexes, unsigned int size)
/* Prints interpolation polynomial in Newton notation */
void print_newton_poly(double *f, double *x, unsigned int n)
{
printf("Newton polynomial form:\n");
for (int i = 0; i < n; i++)
{
printf("(%lf)", f[i]);
for (int j = 0; j < i; j++)
printf("*(x-(%lf))", x[j]);
if (f[i]) // If coefficient != 0
{
/* Coefficient sign and sum symbol */
if (i > 0 && f[i - 1]) // If it's not the first summond
{
if (f[i] > 0)
printf("+ ");
else
printf("- ");
}
else if (f[i] < 0) // If it is the first summond and coefficient is below zero
printf("-");
if (i != n - 1)
printf("+");
printf("%lf", fabs(f[i])); // Print coefficient without sign
for (int j = 0; j < i; j++) // For each (x-xi) bracket
{
if (x[j]) // If summond is not zero, print it
{
if (x[j] > 0)
printf("*(x-%lf)", x[j]);
else
printf("*(x+%lf)", -x[j]);
}
else
printf("*x");
}
printf(" ");
}
}
printf("\n");
}
unsigned int insert_n()
@ -136,12 +170,42 @@ void insert_coords(double *xes, double *yes, unsigned int n)
void print_array(double *arr, unsigned int n)
{
printf("Simplified coefficients array (starting from 0 upto n-1 power):\n");
for (int i = 0; i < n; i++)
printf("%lf ", arr[i]);
printf("\n");
}
void print_poly(double *coef, unsigned int n)
{
printf("Simplified polynom:\n");
for (int i = 0; i < n; i++)
{
if (coef[i])
{
if (i > 0 && coef[i - 1])
if (coef[i] > 0)
printf("+ ");
else
printf("- ");
else
printf("-");
printf("%lf", fabs(coef[i]));
if (i > 0)
printf("*x");
if (i > 1)
printf("^%d ", i);
else printf(" ");
}
}
printf("\n");
}
/*
Main
*/
@ -159,11 +223,13 @@ int main()
print_newton_poly(f, x, n);
double *coeficients = (double *)malloc(sizeof(double) * n);
double *coefficients = (double *)malloc(sizeof(double) * n);
simplify_polynomial(coeficients, f, x, n);
simplify_polynomial(coefficients, f, x, n);
print_array(coeficients, n);
print_array(coefficients, n);
print_poly(coefficients, n);
return 0;
}

6
polynominal_interpolation.h
View File

@ -4,6 +4,11 @@
#include <stdio.h>
#include <stdlib.h>
/*
Utils
*/
double fabs(double x);
/*
Business logic
*/
@ -19,6 +24,7 @@ unsigned int insert_n();
void print_newton_poly(double *f, double *x, unsigned int n);
void insert_coords(double *x, double *y, unsigned int n);
void print_array(double *arr, unsigned int n);
void print_poly(double *coef, unsigned int n);
/*
Coeficients of simplified polynomial computation