Help Creating a Sine Wave in Numbers '09?

Question

Hi,
I'm having trouble graphing some data in Numbers, having been used to Excel for most of my life. What I've basically got to do is graph a sine wave representing the annual variation described in the graph (it compares CO2 concentration measured at a chain of islands to time in years). I've figured out easily how to graph the data on a polynomial treadline curve, but now I've got this to do.
The instructions say to make a new column in column D and enter in the equation 1.435x-2501.1, which is derived from the linear fit treadline equation I had calculated earlier. After that I am to copy it down to match the number of cells in column A (626), which I did, so now every cell in D down to 626 contains that equation above. Then, I enter 1 in cell E1 and 1/12 in order to arbitrarily guess at the sine wave amplitude and period, respectively, and finally I then select cell D1 and put in this equation:
=1.435*A2-2501.1+($E$1*SIN(A2/$F$1))
After that I grab cell D2, drag it down to select all the cells in column D, and add it to the graph by (I think) dragging it onto the graph, as Numbers says to do. What I'm uncertain of is where to go from here. Here are the instructions:
'To plot the model values on the chart, double click or right click on the chart and select "Select Data" and click on Add under Series. Name the series "Model" and select data in column A for the X values and data in column D for the Y values. Rename Series 1 "Raw Data" and click OK."
That's all stuff you can do in Excel... I don't know how to do it in Numbers. When I drag D into the graph, it works fine, but when I go to add in column A for X and D for Y in Inspector it won't let me type anything. How do I complete this sine wave?
Thank you very much in advance for reading through this and helping me.

Answer 1

theleonhearted wrote:
The instructions say to make a new column in column D and enter in the equation 1.435x-2501.1, which is derived from the linear fit treadline equation I had calculated earlier. After that I am to copy it down to match the number of cells in column A (626), which I did, so now every cell in D down to 626 contains that equation above.
I'm not sure of the reason for this step.
1.435x-2501.1
Entered into D2, with the x value in A2 is expressed as:
=1.435*A-2501.1
which is part of the formula below.
Then, I enter 1 in cell E1 and 1/12 in order to arbitrarily guess at the sine wave amplitude and period, respectively, and finally I then select cell D1 and put in this equation:
=1.435*A2-2501.1+($E$1*SIN(A2/$F$1))
I'm assuming "1/12" goes in F1.
I've also assumed row 1 is a Header row, and have entered your formula into the first data row (D2)
Your formula is now:
(1.435 times the value A) - 2501.1 + 1 * (Sin( the value in A divided by 0.833...))
or
(1.435 times the value A) - 2501.1 + 1 * (Sin( the value in A multiplied by 12))
You haven't given any specifics regarding the raw data, so I've arbitrarily set it to a positive linear slope by making A =ROW()-1.
After that I grab cell D2, drag it down to select all the cells in column D, and add it to the graph by (I think) dragging it onto the graph, as Numbers says to do. What I'm uncertain of is where to go from here. Here are the instructions:
'To plot the model values on the chart, double click or right click on the chart and select "Select Data" and click on Add under Series. Name the series "Model" and select data in column A for the X values and data in column D for the Y values. Rename Series 1 "Raw Data" and click OK."
These may be instructions for Excel. Using Numbers, a simpler way to place thie data into an X-y Scatter plot is this:
Set the data up to occupy the full columns A and D, not including the Header row mentioned above.
Select Column A: Click on any cell to make the table active show the row and column Reference tabs.
Click on column A's reference tab.
Command-clickon column D's reference tab to add it to the selection.
Click the Chart button in the tools and choose the Scatter chart icon from the menu.
If I've read this correctly, your formula imposes a sine wave onto the set of data.
Here are the results. The expanded chart at the right shows the approximately the area bounded by the light blue rectangle at the upper end of the plot in the larger chart.
Regards,
Barry