How to calculate value of x-axis and y-axis intersect?

[#1]

Hi Qlikview user,

I have a scatterplot with a linear line.
I want to calculate the following:

• the x value when y=0
• the y value when x = -10

these are the linest_m and linest_b functions:

Linest_m: LINEST_M(aggr(NODISTINCT Avg({TW1}($(vActiveUnitField))),Cofely.Id),aggr(NODISTINCT Avg({TW1}Cofely.Temperature),Cofely.Id))

Linest_b: LINEST_B(aggr(NODISTINCT Avg({TW1}($(vActiveUnitField))),Cofely.Id),aggr(NODISTINCT Avg({TW1}Cofely.Temperature),Cofely.Id))

My scatterplot has the following expressions:

1: Avg({$ * TW2}Cofely.Temperature)

2: Avg({$ * TW2}($(vActiveUnitField)))

dimension:

Cofely.Id (RecNo())

[swuehl · Accepted solution]

You already have the slope m and the y-axis intersection b of the linear equation

y = m*x + b

, so you are all set, aren't you? The rest should be simple:

1) x value for y = 0

0 = m*x + b

---> x = - b/m

2) y value when x = -10

y = m* (-10) + b