Setting intercept for a linear x-y plot
Moderator: DPlotAdmin
Setting intercept for a linear x-y plot
I got the dplot recently and I am wondering how I can set an intercept for a line graph or how I can forecast the line forward or backward. Thanks. Esau, Vancouver
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DPlotAdmin
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It isn't clear to me what you're asking, but here goes:
If you want to fit a line through your existing data and control the value of the Y-intercept, only solving for the slope, then use the "More Curve Fits" command on the Generate menu. Select the polynomial in the "Equation form" list (that's the default selection), enter 1 for the Order, and click the "Initial Values/Constraints" button. Enter the Y-intercept you want for A and check the Hold box.
The "More Curve Fits" function will only generate points between the existing X extents, so it can't be used directly for any sort of forecasting. To do that, use the Y=f(X) command on the Generate menu and enter the equation for your line, then enter whatever extents you want in the "From X" and "To X" boxes.
If you want to fit a line through your existing data and control the value of the Y-intercept, only solving for the slope, then use the "More Curve Fits" command on the Generate menu. Select the polynomial in the "Equation form" list (that's the default selection), enter 1 for the Order, and click the "Initial Values/Constraints" button. Enter the Y-intercept you want for A and check the Hold box.
The "More Curve Fits" function will only generate points between the existing X extents, so it can't be used directly for any sort of forecasting. To do that, use the Y=f(X) command on the Generate menu and enter the equation for your line, then enter whatever extents you want in the "From X" and "To X" boxes.
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