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In Microsoft Excel there is a SLOPE function. What I need to do is translate the formula of this SLOPE function to work in a Visual C++ Application. Can anyone out there show me how I would write the function or functions that will produce the same output as the Excel SLOPE function! I can provide more information as needed, but would appreciate as detailed information as possible! PLEASE HELP!
Many thanks!
Charlie
Linear line regression algorithm is very easy to implement. I never use Excel SLOPE function. I suppose, that parameters are array of x,y points, the slope of a line( steepness of the line) and intercept.
But I'm not sure, how is this algorithm implemented in Excel. Let me detailed information, if you want.
I need the details if you can provide please do so!
Thanks
In this WEB site you can find explanation.
http://www.ruf.rice.edu/~lane/hyperstat/A115370.html
I never used Excel, so I need to know, what kind of input data you use.
I don't know what SLOPE does, but to find the
"least squares regression line" , y = Mx + B
for the points (x(i),y(i)) for i = 1,N
you would do the following :
s0 = N+1
s1 = sum_of(x(i)) for i = 1,N
s2 = sum_of(x(i)*x(i)) for i = 1,N
t0 = sum_of(y(i)) for i = 1,N
t1 = sum_of(x(i)*y(i)) for i = 1,N
then
M = ( s0*t1 - s1*t0 ) / (s0*s2 - s1*s1)
B = ( s2*t0 - s1*t1 ) / (s0*s2 - s1*s1)
and the regression line is given by
y = Mx + B
A B Slope
1.05 0.016632 0.015338
1.05 0.016817
1.05 0.016662
3.05 0.047281
3.05 0.047469
3.05 0.047494
5.05 0.079046
5.05 0.078907
5.05 0.078804
10.05 0.155113
10.05 0.154559
10.05 0.154475
If you open Excel and add the data (not the slope value) The in a column off to the right add the slope function and it should look like this
SLOPE(B2:B13,A2:A13)
If you need more info please let me know.
Thanks!
Charlie
Thank you, I take a look on this through the weekend. I'm very busy during working week....
Can you send me your email adress? My is in my profile on codeguru.
f.y.i. the algorithm that I gave you calculated the same slope that
you provided in your sample data set.
Here is a code snippet to do the calculation :
// values needed prior to code snippet
//
// int n = number of (x,y) points
// double x[ i ] for i = 0 to n-1 ... the x points
// double y[ i ] for i = 0 to n-1 ... the y points
//
double s0 = 0;
double s1 = 0;
double s2 = 0;
double t0 = 0;
double t1 = 0;
for (int i=0; i<n; i++)
{
s0++;
s1 = s1 + x[ i ];
s2 = s2 + x[ i ]*x[ i ];
t0 = t0 + y[ i ];
t1 = t1 + x[ i ]*y[ i ];
}
double M = ( s0*t1 - s1*t0 ) / (s0*s2 - s1*s1) ; // slope
double B = ( s2*t0 - s1*t1 ) / (s0*s2 - s1*s1) ; // y-intercept
SORRY! I didn't understand your original message, but this is exactly what I was looking for! So I will give it a try and I appreciate your extra effort in providing the information in a more understandable format!
Thanks!
Charlie
Hi thanks for this code,but can you help me to get the regression..y=mx+b? what is the value of x? is it the iteration of data or the total absorbance? or conc? Please email me at jotyme@rocketmail.com. Thanks bro.Quote:
Originally Posted by Philip Nicoletti