Determine the equivalent width of a model component.
XSPEC> eqwidth [[RANGE <frac range>] <model component number>]...
The command calculates the integrated photon flux produced by an additive model component (FLUX), the location of the peak of the photon spectrum (E), and the flux (photons per keV) at that energy of the continuum (CONTIN). The equivalent width is then defined as EW = FLUX / CONTIN in units of keV. The continuum is defined to be those other components of the selected model's additive group (see the model command). Thus, neither components in other additive groups nor the effect of any multiplicative components (e.g., absorption) are used in the calculation of the continuum or the equivalent width.
There are certain models with a lot of structure where, were they the continuum, it might be inappropriate to estimate the continuum flux at a single energy. The continuum model is integrated (from E(1-<frac range>) to E(1+<frac range>). The initial value of <frac range> is 0.05 and it can changed using the ŖANGE keyword.