#include "common.h"
#include <stdlib.h>
#include <alloc.h>
#include <math.h>


Polynomial::Polynomial(){
    float coeffs[1];
    coeffs[0] = 1;
    init(1, coeffs);
}

Polynomial::Polynomial(int numcoeffs, float coeffs[]){
    init(numcoeffs, coeffs);
}

void Polynomial::init(int numcoeffs, float coeffs[]) {
    this->coeffs = (float *) calloc((size_t) numcoeffs, (size_t) sizeof(float));
    int i;
    float *ptr = coeffs;
    for(i=0;i<numcoeffs;i++) {
        this->coeffs[i] = *ptr; 
        ptr++;
    }
    degree = numcoeffs-1;
}

Polynomial::~Polynomial() {
    free((void *) coeffs);
}

float Polynomial::value(float x) {
    float y = coeffs[0];
    int i;
    for(i=1;i<=degree;i++){
        y += pow(x, i) * coeffs[i];
    }
    return y;
}

void Polynomial::describe() {
    int i;
    for(i=degree;i>=0; i--){
        if(coeffs[i] >= 0) {
            if(i<degree){
                cout << "+";
            }
        } else {
            cout << "-";
        }
        cout << fabs((double)coeffs[i]) << "x^" << i ;
    }
}

void output(float x, Polynomial *p0, Polynomial *p1, Polynomial *p2, Polynomial *p3, Polynomial *p4) {
    cout << "x=" << x << "  p0(x)=" <<p0->value(x)<< "  p1(x)=" <<p1->value(x)<< "  p2(x)=" <<p2->value(x)<< "  p3(x)=" <<p3->value(x)<< "  p4(x)=" <<p4->value(x)<< "\n";
}