# Include <stdio. h>
# Include <conio. h>
# Include <math. h>
# Include <process. h>
# Define N 5 // n points
# Define T 3 // t fitting
# Define W 1 // Weight Function
# Define precision 0.00001
Float pow_n (float a, int N)
{
Int I;
If (n = 0)
Return (1 );
Float res =;
For (I = 1; I <n; I ++)
{
Res * =;
}
Return (RES );
}
Void mutiple (float a [] [N], float B [] [t + 1], float C [] [t + 1])
{
Float res = 0;
Int I, J, K;
For (I = 0; I <t + 1; I ++)
For (j = 0; j <t + 1; j ++)
{
Res = 0;
For (k = 0; k <n; k ++)
{
Res + = A [I] [k] * B [k] [J];
C [I] [j] = res;
}
}
}
Void matrix_trans (float a [] [T + 1], float B [] [N])
{
Int I, j;
For (I = 0; I <N; I ++)
{
For (j = 0; j <T + 1; j ++)
{
B [j] [I] = a [I] [j];
}
}
}
Void init (float x_y [] [2], int n)
{
Int I;
Printf ("Enter % d known points:/n", N );
For (I = 0; I <n; I ++)
{
Printf ("(x % d y % d):", I, I );
Scanf ("% f", & x_y [I] [0], & x_y [I] [1]);
}
}
Void get_A (float matrix_A [] [T + 1], float x_y [] [2], int n)
{
Int I, j;
For (I = 0; I <N; I ++)
{
For (j = 0; j <T + 1; j ++)
{
Matrix_A [I] [j] = W * pow_n (x_y [I] [0], j );
}
}
}
Void print_array (float array [] [T + 1], int n)
{
Int I, j;
For (I = 0; I <n; I ++)
{
For (j = 0; j <T + 1; j ++)
{
Printf ("%-g", array [I] [j]);
}
Printf ("/n ");
}
}
Void convert (float argu [] [T + 2], int n)
{
Int I, j, k, p, t;
Float rate, temp;
For (I = 1; I <n; I ++)
{
For (j = I; j <n; j ++)
{
If (argu [I-1] [I-1] = 0)
{
For (p = I; p <n; p ++)
{
If (argu [p] [I-1]! = 0)
Break;
}
If (p = n)
{
Printf ("no solution to the equations! /N ");
Exit (0 );
}
For (t = 0; t <n + 1; t ++)
{
Temp = argu [I-1] [t];
Argu [I-1] [t] = argu [p] [t];
Argu [p] [t] = temp;
}
}
Rate = argu [j] [I-1]/argu [I-1] [I-1];
For (k = I-1; k <n + 1; k ++)
{
Argu [j] [k]-= argu [I-1] [k] * rate;
If (fabs (argu [j] [k]) <= PRECISION)
Argu [j] [k] = 0;
}
}
}
}
Void compute (float argu [] [T + 2], int n, float root [])
{
Int I, j;
Float temp;
For (I = n-1; I> = 0; I --)
{
Temp = argu [I] [n];
For (j = n-1; j> I; j --)
{
Temp-= argu [I] [j] * root [j];
}
Root [I] = temp/argu [I] [I];
}
}
Void get_y (float trans_a [] [N], float x_y [] [2], float y [], int N)
{
Int I, J;
Float temp;
For (I = 0; I <n; I ++)
{
Temp = 0;
For (j = 0; j <n; j ++)
{
Temp + = trans_a [I] [J] * x_y [J] [1];
}
Y [I] = temp;
}
}
Void cons_formula (float coef_a [] [t + 1], float y [], float coef_form [] [t + 2])
{
Int I, J;
For (I = 0; I <t + 1; I ++)
{
For (j = 0; j <t + 2; j ++)
{
If (j = t + 1)
Coef_form [I] [J] = Y [I];
Else
Coef_form [I] [J] = coef_a [I] [J];
}
}
}
Void print_root (float a [], int N)
{
Int I, J;
Printf ("% d points of % d fitting polynomial coefficients:/n", N, T );
For (I = 0; I <n; I ++)
{
Printf ("a [% d] = % g,", I + 1, a [I]);
}
Printf ("/n ");
Printf ("fitting curve equation:/ny (x) = % g", a [0]);
For (I = 1; I <n; I ++)
{
Printf ("+ % g", a [I]);
For (j = 0; j <I; j ++)
{
Printf ("* X ");
}
}
Printf ("/n ");
}
Void process ()
{
Float x_y [N] [2], matrix_A [N] [T + 1], trans_A [T + 1] [N], coef_A [T + 1] [T + 1], coef_formu [T + 1] [T + 2], y [T + 1], a [T + 1];
Init (x_y, N );
Get_A (matrix_A, x_y, N );
Printf ("matrix A:/n ");
Print_array (matrix_A, N );
Matrix_trans (matrix_A, trans_A );
Mutiple (trans_A, matrix_A, coef_A );
Printf ("method matrix:/n ");
Print_array (coef_A, T + 1 );
Get_y (trans_A, x_y, y, T + 1 );
Cons_formula (coef_A, y, coef_formu );
Convert (coef_formu, T + 1 );
Compute (coef_formu, T + 1, );
Print_root (a, T + 1 );
}
Void main ()
{
Process ();
}
]>
</Content>
<PostDateTime> 19:23:57 </PostDateTime>
</Reply>
<Reply>
<PostUserNickName> </PostUserNickName>
<Rank> Level 1 (Elementary) </rank>
<Ranknum> user1 </ranknum>
<Credit> 100 </credit>
<ReplyID> 40389872 </ReplyID>
<TopicID> 5478010 </TopicID>
<PostUserId> 1526752 </PostUserId>
<PostUserName> jiangxc2004 </PostUserName>
<Point> 0 </Point>
<Content>
<! [CDATA [
You can change it.
If you do not enter parameters from the terminal, enter five known points in the program:
(X0 y0):-2-0.1
(X1 y1):-1 0.1
(X2 y2): 0 0.4
(X3 y3): 1 0.9
(X4 y4): 2 1.6
Matrix A is:
1-2 4-8
1-1 1-1
1 0 0 0
1 1 1 1
1 2 4 8
Algorithm matrix:
5 0 10 0
0 10 0 34
10 0 34 0
0 34 0 130
The polynomial coefficients of three fitting for five points are:
A [1] = 0.408571, a [2] = 0.391667, a [3] = 0.0857143, a [4] = 0.00833333,
The fitting curve equation is:
Y (x) = 0.408571 + 0.391667 * x + 0.0857143 * x + 0.00833333 * x]>
</Content>
<Postdatetime> 19:26:11 </postdatetime>
</Reply>
<Reply>
<Postusernickname> </postusernickname>
<Rank> Level 1 (Elementary) </rank>
<Ranknum> user1 </ranknum>
<Credit> 100 </credit>
<Replyid> 40390406 </replyid>
<Topicid> 5478010 </topicid>
<Postuserid> 1526752 </postuserid>
<PostUserName> jiangxc2004 </PostUserName>
<Point> 0 </Point>
<Content>
<! [CDATA [
In this way, you can directly call the process () function! If the second fitting is done, the macro T will be 2;
The number of fitting points N can also be modified!
You can also go to the comments to call the return value!
