interpo.c

#include <stdio.h>
#include <stdlib.h>
float interpol_Lagrange(int n, float abs[n], float ord[n], float x);
float lix (int n, float abs[n], float x, int ind);
float interpol_Newton(int n, float abs[n], float ord[n], float x, int deg, float *b);
float difdiv(float* abs, float* ord, int deg, int ind);
void remplir_b(float* abs, float* ord, int n, float b[n]);
void remplir_dens(float* abs,float* ord);
void remplir_revenu(float* abs,float*  ord);

int main()
{
    float i = 0;
    float x,res;
    float abs[20];
    float ord[20];
    float b[20];
    remplir_dens(abs,ord);
    remplir_b(abs,ord,20,b);

    while(i < 40)
    {
        res=interpol_Newton(20,abs,ord,i,19,b);
        printf("%f : %f\n",i ,res);
        i += 0.5;
    }



    return (0);
}

float interpol_Lagrange(int n, float abs[n], float ord[n], float x)
{
    int i = 0;
    float poly = 0;

    for(i = 0; i < n; i++)
    {
        poly += ord[i] * lix(n, abs, x, i);
    }

    return poly;
}

float lix (int n, float abs[n], float x, int ind)
{
    int j;
    float pi = 1;

    for(j = 0; j < n; j++)
    {
        if (j != ind)
        {
            pi = pi*((x-abs[j])/(abs[ind]-abs[j]));
        }

    }

    return (pi);
}

float interpol_Newton(int n, float abs[n], float ord[n], float x, int deg, float *b)
{
    float res;

    if (deg == 0)
        return b[n - 1];

    else
    {
        res = b[n - deg - 1] + (x - abs[n - deg - 1]) * interpol_Newton(n, abs, ord, x, deg - 1, b);
        return res;
    }
}

float difdiv(float* abs, float* ord, int deg, int ind)
{
    float dif;
    if (ind<deg)
        return 0;
    if (deg==0)
    {
        dif=ord[ind];
    }
    else if (deg==1)
        dif=(ord[ind]-ord[0])/(abs[ind]-abs[0]);

        else
        {
            dif =(difdiv(abs,ord,deg-1,ind) - difdiv(abs,ord,deg-1,deg-1))/(abs[ind]-abs[deg-1]);
        }
    return (dif);
}

void remplir_b(float* abs, float* ord, int n, float b[n])
{
    int i;
    for (i=0;i<n;i++)
    {
        b[i]=difdiv(abs,ord,i,i);
        //printf("%f",b[i]);
    }

}

void remplir_dens(float* abs,float*  ord)
{
    float abs1[20]={0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38};
    float ord1[20]={0.99987,0.99997,1,0.99997,0.99988,0.99973,0.99953,0.99927,0.99289,0.99846,0.99805,0.999751,0.99705,0.99650,0.99664,0.99533,0.99472,0.99472,0.99333,0.99326};
    int i;
    for (i=0;i<20;i++)
    {
        abs[i]=abs1[i];
        ord[i]=ord1[i];
    }
}


void remplir_revenu(float* abs,float*  ord)
{
    float abs1[21]={752,855,871,734,610,582,221,492,569,462,907,643,862,524,679,902,918,828,875,809,894};
    float ord1[21]={85,83,162,79,81,83,281,81,81,80,243,84,84,82,80,226,260,82,186,77,223};
    int i;
    for (i=0;i<21;i++)
    {
        abs[i]=abs1[i];
        ord[i]=ord1[i];
    }
}