Origin Version (Select Help-->About Origin): Origin v7.5
Operating System:Windows 2000
when i write a test linear fit arithmetic to make a line:Y = kX + b.
but the result is always different from the origin linear fit.may be i miss something in my programe,can someone help me?Thanks very much.
My Code is as follow:
#include <stdio.h>
#define MAXNODE 24
double sum1(double a[],int n)
{
double y=0; int i;
for(i=0;i<n;i++)
y+=a[i];
return(y);
}
double sum2(double a[],int n)
{
double y=0; int i;
for(i=0;i<n;i++)
y+=a[i]*a[i];
return(y);
}
double sum3(double a[], double b[],int n)
{
double y=0; int i;
for(i=0;i<n;i++)
y+=a[i]*b[i];
return(y);
}
int main()
{
double a,b;
int N = 24;
double x[24] = {0.00186,
0.00185,
0.00184,
0.00184,
0.00183,
0.00182,
0.00181,
0.0018,
0.00179,
0.00179,
0.00178,
0.00177,
0.00176,
0.00176,
0.00175,
0.00174,
0.00173,
0.00172,
0.00172,
0.00171,
0.0017,
0.0017,
0.00169,
0.00168};
double y[24] = {-13.71611,
-13.6033,
-13.58863,
-13.48522,
-13.47886,
-13.39108,
-13.33716,
-13.27675,
-13.23764,
-13.16014,
-13.0996,
-13.05467,
-12.97989,
-12.95996,
-12.92921,
-12.84708,
-12.83526,
-12.77366,
-12.68855,
-12.66473,
-12.65777,
-12.60471,
-12.5354,
-12.45963};
a=(N*sum3(x,y,N)-sum1(x,N)*sum1(y,N))/(N*sum2(x,N)-sum1(x,N)*sum1(x,N));
b=(sum1(y,N)*sum2(x,N)-sum1(x,N)*sum3(x,y,N))/(N*sum2(x,N)-sum1(x,N)*sum1(x,N));
printf("Result is:\n y=%f x + %f\n",a,b);
return 0;
}
my result is:y=-6694.250717 x + -1.219209
And the origin result log is:
[2007-7-22 12:19 "/Graph1" (2454303)]
Linear Regression for Data3_B:
Y = A + B * X
Parameter Value Error
------------------------------------------------------------
A -1.27315 0.1525
B -6662.66738 86.18488
------------------------------------------------------------
R SD N P
------------------------------------------------------------
-0.99816 0.02291 24 <0.0001
Edited by - 70WorkRoom on 07/22/2007 01:31:33 AM
