Absolute Error

Absolute error is the magnitude of the difference between an approximate value and the exact value.

$$E_{\text{abs}}=|y_{\text{approx}}-y_{\text{exact}}|$$

Absolute error gives a straightforward measure of how far off an approximation is, in the same units as the quantity being measured. It does not account for the scale of the quantity itself - see Relative error for a scale-independent measure.

Absolute error appears naturally in the definition of Local truncation error and Global truncation error, and in the convergence analysis of numerical ODE methods.

Relative error | Local truncation error | Global truncation error | Order of a method