Synopsis
		sfderiv < in.rsf > out.rsf order=6 scale=n

May 2012 program of the month:
http://ahay.org/blog/2012/05/01/program-of-the-month-sfderiv/

Parameters
		int order=6 filter order   bool scale=n [y/n] if scale by 1/dx

Used In
		DIRACK          examples/crestack examples/modelAndStack examples/pefInterpolation   GALLERY          french/gazdag french/lowrank french/model french/oway french/stolt french/vc gradient/fakirmig gradient/lowrank gradient/model gradient/oway vofz/gazdag vofz/kirch vofz/lowrank vofz/model vofz/oway vofz/stolt vofz/vc   GEO384W          hw3/synth hw4/synth   JLU          gvdseisint/ocmodel txyapf/french txyspfint/french   MILANO          taupvel/cmp taupvel/synth   RSF          rsf/sfderiv rsf/sfnderiv school/trig school2017/gravity school2020/gravity su/rsflab8 su/rsfmodel tutorials/lineaments tutorials/semblance tutorials/smoothing   SEP          oc2/cup   SWAG          tau/hess tau/iso tau/lens tau/marm   TCCS          eikods/migration nmo3/azimuthtest nmodeblend/class nmodeblend/synth oc3/french oc3/frenchint pmig/mig pmig/nmo probdif/nankai probdif/noisy-synthetic probdif/synthetic probdif/toy reversible/nscnmo sobel/penobscot svmf/class svscan/class varipick/global-gom varipick/horizon varipick/newviking vscan/hw welllogs/logs wetm/synthetic4