SUBROUTINE THOLIN(WAVELN,XNR,XNI)
      DIMENSION W(90),XN(90),XK(90)
      DATA W/
     &920.0000,850.0000,774.9000,688.8000,563.5000,387.4000,229.6000,
     &172.2000,140.9000,121.5000, 81.5700, 56.3500, 36.4600, 31.0000,
     & 22.1400, 18.2300, 17.7100, 14.4200, 12.9100, 11.7000, 11.0700,
     & 10.5100,  8.7310,  7.6530,  7.0440,  6.6660,  6.4570,  6.3260,
     &  5.9610,  5.8480,  5.7400,  5.4380,  5.2530,  5.1660,  4.8810,
     &  4.6260,  4.5920,  4.4920,  4.4280,  4.2170,  3.9480,  3.6680,
     &  3.4630,  3.2460,  3.0090,  2.9380,  2.8180,  2.7430,  2.6950,
     &  2.4220,  2.4030,  2.3930,  2.2140,  2.0190,  1.8730,  1.8230,
     &  1.8130,  1.8020,  1.3810,  1.3570,  1.1920,  1.1480,  1.0160,
     &  0.8731,  0.6888,  0.5635,  0.4428,  0.4133,  0.3874,  0.3542,
     &  0.3263,  0.2952,  0.2638,  0.2384,  0.1968,  0.1631,  0.1362,
     &  0.1215,  0.1181,  0.1159,  0.1097,  0.1016,  0.0925,  0.0800,
     &  0.0785,  0.0588,  0.0449,  0.0415,  0.0312,  0.0207/
      DATA XN/
     &2.170,2.170,2.160,2.160,2.150,2.120,2.070,2.040,2.030,2.020,1.930,
     &1.860,1.810,1.810,1.800,1.760,1.740,1.670,1.670,1.640,1.660,1.670,
     &1.710,1.720,1.690,1.690,1.640,1.580,1.430,1.440,1.480,1.550,1.580,
     &1.580,1.610,1.620,1.610,1.610,1.610,1.630,1.640,1.650,1.650,1.650,
     &1.610,1.590,1.580,1.590,1.600,1.620,1.620,1.620,1.630,1.630,1.630,
     &1.640,1.640,1.640,1.640,1.640,1.650,1.650,1.650,1.660,1.680,1.700,
     &1.720,1.690,1.660,1.630,1.640,1.660,1.680,1.680,1.660,1.650,1.700,
     &1.740,1.750,1.750,1.720,1.670,1.580,1.370,1.330,0.963,0.812,0.802,
     &0.850,0.920/
      DATA XK/
     &3.0E-3,1.0E-2,2.9E-2,4.7E-2,7.0E-2,1.0E-1,1.4E-1,1.6E-1,1.6E-1,
     &1.9E-1,2.1E-1,1.9E-1,1.5E-1,1.4E-1,1.8E-1,2.1E-1,2.1E-1,1.7E-1,
     &1.4E-1,9.7E-2,7.9E-2,7.5E-2,9.2E-2,1.3E-1,1.7E-1,2.2E-1,2.6E-1,
     &2.8E-1,1.5E-1,7.0E-2,2.9E-2,1.1E-2,8.7E-3,7.6E-3,1.0E-2,2.7E-2,
     &2.8E-2,1.4E-2,1.1E-2,1.0E-2,1.3E-2,2.1E-2,3.5E-2,5.6E-2,7.5E-2,
     &6.0E-2,2.4E-2,1.1E-2,4.1E-3,1.2E-3,8.5E-4,8.0E-4,8.9E-4,7.2E-4,
     &5.2E-4,4.4E-4,4.2E-4,4.0E-4,4.1E-4,4.2E-4,5.2E-4,6.4E-4,1.0E-3,
     &2.4E-3,8.8E-3,2.3E-2,6.0E-2,7.6E-2,9.1E-2,1.1E-1,1.3E-1,1.5E-1,
     &1.8E-1,2.1E-1,2.2E-1,2.4E-1,2.7E-1,3.7E-1,4.0E-1,4.3E-1,5.0E-1,
     &5.8E-1,6.7E-1,7.7E-1,7.7E-1,6.2E-1,3.8E-1,3.1E-1,1.4E-1,4.9E-2/
      XNR=XN(1)
      XNI=XK(1)
      IF (WAVELN .GT. W(1))  RETURN
      XNR=XN(90)
      XNI=XK(90)
      IF (WAVELN .LT. W(90)) RETURN
      DO 100 I=2,90
      IF (WAVELN .GT. W(I) ) GO TO 101
 100  CONTINUE
 101  CONTINUE
C ALL INTERPOLATION IS IN LOG LAMBDA
      FACTOR= (alog(WAVELN) - alog(W(I)) ) / (alog(W(I-1)) - alog(W(I)))
C REAL PART IS LINEARLY INTERPOLATED
      XNR=XN(I) + FACTOR*(XN(I-1) - XN(I))
C IMAGINARY PART IS LOG INTERPOLATED
      XNI=alog(XK(I)) + FACTOR*(alog(XK(I-1)) - alog(XK(I)))
      XNI=exp(XNI)
      RETURN
      END