'Slope' function help needed

[illini_dill]

I am in need of a Slope function. I know the forumla for Slope, but cannot find a pre-written function. There must be one out there somewhere. Does anyone have any ideas?

Question 2- Excel has a slope funtion. Is it possible to access it from .Net? I have tried but cannot figure it out short of exporting all the data to a spreadsheet and then calling the function. Can I implement excel functions in .net code (local to the code)?

Thanks in advance.

[nemaroller]

Correct me if I'm off base here, but there must be some other restriction to your question, because if you have the formula, you could easily write your own slope function.

Private Function GetSlope(ByVal x1 as double, ByVal x2 as Double, _ 
 ByVal y1 as double, ByVal y2 as Double) As Double
 
GetSlope = y2-y1 / x2-x1
Return GetSlope
End Function

[Kasracer]

Originally posted by nemaroller
Correct me if I'm off base here, but there must be some other restriction to your question, because if you have the formula, you could easily write your own slope function.

Yeah... I am wondering why the poster asked this question... you just subtract 2 sets of numbers and divide......

[jsiegendorf]

Function ComputeSlope(ByVal arrY() As Double, ByVal arrX() As Double) As Double

' Define equation variables
Dim n As Integer = arrX.GetLength(0)
Dim Slope As Double
Dim Intercept As Double

' Get required summations
Dim i As Integer
Dim sumX As Double = 0
Dim sumY As Double = 0
Dim sumXY As Double = 0
Dim sumX2 As Double = 0
For i = 0 To (n - 1)
sumX += arrX(i)
sumY += arrY(i)
sumXY += arrX(i) * arrY(i)
sumX2 += arrX(i) ^ 2
Next

Slope = ((n * sumXY) - (sumX * sumY)) / ((n * sumX2) - (sumX ^ 2))
Intercept = (sumY - (Slope * sumX)) / n

Return Slope

End Function

[Kasracer]

Originally posted by jsiegendorf
Function ComputeSlope(ByVal arrY() As Double, ByVal arrX() As Double) As Double

' Define equation variables
Dim n As Integer = arrX.GetLength(0)
Dim Slope As Double
Dim Intercept As Double

' Get required summations
Dim i As Integer
Dim sumX As Double = 0
Dim sumY As Double = 0
Dim sumXY As Double = 0
Dim sumX2 As Double = 0
For i = 0 To (n - 1)
sumX += arrX(i)
sumY += arrY(i)
sumXY += arrX(i) * arrY(i)
sumX2 += arrX(i) ^ 2
Next

Slope = ((n * sumXY) - (sumX * sumY)) / ((n * sumX2) - (sumX ^ 2))
Intercept = (sumY - (Slope * sumX)) / n

Return Slope

End Function

You could cut out about half that crap. Also, why bother find Intercept when it doesn't return it?

[jsiegendorf]

The slope function in Excel takes two arrays as inputs. Perhaps the original poster was interested in more than just two numbers.

Also, I originally wrote this function to return both. Even though the question only called for slope, it is not out of the question that the user might need to get the intercept eventually.