# Unable to Draw Custom Curve on Semi-Log Scatter Plot with X-Axis Dates

Hi,

I have a scatter plot on which I would like to draw my own curve fit. The plot is semi-log, with dates along the x-axis.

I am having difficulty developing an equation that shows up on the graph. After some failed trial and error with adding a **Custom Curve**, my next idea was to begin by copying the equation from the automatic **Straight Line Fit**, to ensure that the equation I am using would generate a line in the general area of the plot where I want the final line, then I could manually tweak the **Custom Curve** equation to get the final trend I want.

Below I have included a screenshot to illustrate what I have tried: I have use the **Straight Line Fit** to generate the equation Log10(y) = 131.22 + 2.01E-16*X. However, when I enter this same into a **Custom Curve** equation, no line is drawn on my graph (Yes, I have ticked the tick box to check :)). Are there adjustments that need to be made in the **Curve expression** for the semi-log plot?

Something else suspicious: When the **Curve Draw** curve I have generated is selected in the **Visible Lines and Curves** menu, all of the options underneath **Label and Tootip...** button are greyed out (Include in axis range, Update manually, One per Color, etc). This leads me to believe that Spotfire does not like the equation I have entered and it not calculating it at all, despite the fact that the **Status** box below the **Curve expression** says OK.

Can anyone advise? I am at a loss for what else to try. For reference, I am using v. 7.6.0.61. Thanks!

## 1 Comment

A hint to the problem is already visible in the function plotted in the graph, namely it is assuming a logarithmic function now log(y)=F(x)

Try putting in following function:

log10(131.22 + 2.01E-16*X)