VBA Linear Interpolation

Hi All

I have a quarterly US GDP data from 1980 to date. The problem I have is given the data is only produced quarterly I have gaps in the data. This is fine when drawing a chart in excel as you can simply join data points however, an external provider I use to publish charts does not have this feature on its software and I am required to provide a value for every date. I therefore need to interpolate (linear) the values between data points. This is easily done manually on a small data set however I wonder if anyone has a piece of VBA code to speed things up.

Thanks

There's one value for GDP, which makes it a little hard to see what you want interpolated.

EDIT: Never mind, I see it ...

You want GDP for every day?? That's kind of empty magnification, isn't it?

I used AutoFilter to extract the quarterly numbers, and a UDF to do the interpolation:

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The formula in E2 and down is

=LINTERP(D2, $A$2:$A$121, $B$2:$B$121)

Here's the UDF:

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