procedure abzero (w, logf) real w {prompt="Wavelength (microns)"} real logf {prompt="Log f_lambda (W/cm^2/micron)"} begin x = 10000 * w y = -2.5 * (logf + 3) - 5 * log10 (x) - 2.4 printf ("%d %.3f\n", x, y) end