function mfilt(kx,ky,mx,my,mz,fx,fy,fz,z1,z2) c c Function MFILT calculates the complex value of the earth c filter at a single (kx,ky) location. c c Input parameters: c kx - the wavenumber coordinate in the kx direction. c ky - the wavenumber coordinate in the ky direction. c mx - the x direction cosine of the magnetization vector. c my - the y direction cosine of the magnetization vector. c mz - the z direction cosine of the magnetization vector. c fx - the x direction cosine of the regional field vector. c fy - the y direction cosine of the regional field vector. c fz - the z direction cosine of the regional field vector. c z1 - the depth to the top of the layer. c z2 - the depth to the bottom of the layer. c c Output parameters: c mfilt - the complex value of the earth filter. c complex mfilt,thetam,thetaf,cmplx real kx,ky,k,mx,my,mz data pi/3.14159265/,cm/1.e-7/ k=sqrt(kx**2+ky**2) if(k.eq.0.)then mfilt=0. else thetam=cmplx(mz,(kx*mx+ky*my)/k) thetaf=cmplx(fz,(kx*fx+ky*fy)/k) mfilt=2.*pi*cm*thetam*thetaf*(exp(-k*z1)-exp(-k*z2)) end if return end