“Global” functions

$\phi \left(r\right)$

Thin-Plate Spline (TPS)

${\left(\epsilon r\right)}^2\log \left(\epsilon r\right)$

Gauss function

$\exp \left(-{\left(\epsilon r\right)}^2\right)$

Inverse Quadric(IQ)

$\text{1}/\left(\text{1+}{\left(\epsilon r\right)}^2\right)$

Inverse Multiquadric (IMQ)

$\text{1}/\sqrt{\text{1+}{\left(\epsilon r\right)}^2}$

Multiquadric (MQ)

$\sqrt{\text{1+}{\left(\epsilon r\right)}^2}$