3.172 FAQ-1230 Why is Gravity Center from peak analysis missing for some peaks?

Last Update: 12/18/2025

Sometimes, after fitting a spectrum with Peak Analyzer, the gravity center of a peak is reported as missing value "--" even though the overall fit looks good.

The value is intentionally left blank for certain built-in functions (e.g., PearsonVII) whose moments may not exist. For example, in PearsonVII function, when m < 1 the product x*f(x) does not converge to 0 as x approaches to infinity, and thus its integral from -inf to inf diverges. Because the center of gravity is undefined in this case, Origin skips the calculation and reports a missing value. 


Keywords:Pearson, peak fit, gravity center, peak analysis