Logarithmic axes cannot contain zero or negative numbers 

Logarithmic axes cannot contain zero or negative numbers 


The logarithms of negative numbers and zero are simply not defined
Let’s start with the fundamental definition of a logarithm. If 10L = Z, then L is the logarithm (base 10) of Z. If L is a negative value, then Z is a positive fraction less than 1.0. If L is zero, then Z equals 1.0. If L is greater than 0, then Z is greater than 1.0. Note that there no value of L will result in a value of Z that is zero or negative. Logarithms are simply not defined for zero or negative numbers.
Bottom line: A logarithmic axis can only plot positive values. There simply is no way to put negative values or zero on a logarithmic axis.
A trick to plot zero on a logarithmic axis in Prism
If you really want to include zero on a logarithmic axis, you’ll need to be clever. Don’t enter 0, instead enter as a small number. For example, if the smallest value in your data is 0.01, enter the zero value as 0.001. Then use the Format Axis dialog to create a discontinuous axis, and use the Additional ticks feature of Prism to label that spot on the axis as 0.0.