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Numbers for Mac polynomial trendline not showing all terms

Hi,


I'm using 5th and 6th-order polynomial trendlines in my chart. I have displayed the equation, but it only shows up to an x^4 term. For 3rd order, it shows x^3..x^0 terms, for 4th order, it shows x^4..x^0 terms. These are as expected, but for 5th order and 6th order, it still shows only x^4..x^0 terms. The coefficients on these terms change, so the underlying trendline equation is changing, and the trendline curve on my chart fits my data better, but it's not showing the higher-order coefficients. I'm thinking this is a bug, but before I send Apple feedback, I thought I'd ask here.


Also, while I don't think this is a bug, it's annoying. When a coefficient can fit into four decimal places, it doesn't display scientific notation. For example, 0.0004. The problem is that if this coefficient is on a higher-order term (e.g., x^4), then the values the equation produces can be very sensitive to the lack of significant figures. I actually wish I could control how many significant figures it displayed. I'd love a function that would return an array of coefficients. Oh well.


I'm running macOS Catalina 10.15.3 and Numbers 6.2.1.


Best, Eric

MacBook Pro 16", macOS 10.15

Posted on Mar 25, 2020 12:33 PM

Reply
5 replies

Apr 14, 2020 12:53 AM in response to Eric Goodill1

Hi Eric and Xantheman,


Tested in Numbers 10.0 under macOS Catalina.

Polynomial Trendline allows up to Order 6.

Table 1 has one Header Column (unused) and one Header Row.

Data are in Body Cells.

I selected Columns B and C and inserted a Scatter plot.

Insert a Polynomial Trendline and then click on the line to change the Order.



If this does not work for you, I hope that Apple's iWork team can help you.

Regards,

Ian.

Apr 13, 2020 11:20 AM in response to Xantheman

Xantheman,


Glad to know it's not just me. I actually got an email from "iwork@apple.com" claiming to be Apple's iWork team asking for the file so they could debug the problem. Since the file had no sensitive info (I hope), I sent it to that address. Let's hope that really is the iWork team and that they can find and fix the bug.


Best, Eric

Numbers for Mac polynomial trendline not showing all terms

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