[u/mrichter/AliRoot.git] / MINICERN / mathlib / gen / f / tred2.F

*
* $Id$
*
* $Log$
* Revision 1.1.1.1  1996/04/01 15:02:38  mclareni
* Mathlib gen
*
*
#include "gen/pilot.h"
      SUBROUTINE TRED2(NM,N,A,D,E,Z)
      INTEGER I,J,K,L,N,II,NM,JP1
      REAL A(NM,N),D(N),E(N),Z(NM,N)
      REAL F,G,H,HH,SCALE
      DO 100 I = 1, N
         DO 100 J = 1, I
            Z(I,J) = A(I,J)
  100 CONTINUE
      IF (N .EQ. 1) GO TO 320
      DO 300 II = 2, N
         I = N + 2 - II
         L = I - 1
         H = 0.0
         SCALE = 0.0
         IF (L .LT. 2) GO TO 130
         DO 120 K = 1, L
  120    SCALE = SCALE + ABS(Z(I,K))
         IF (SCALE .NE. 0.0) GO TO 140
  130    E(I) = Z(I,L)
         GO TO 290
  140    DO 150 K = 1, L
            Z(I,K) = Z(I,K) / SCALE
            H = H + Z(I,K) * Z(I,K)
  150    CONTINUE
         F = Z(I,L)
         G = -SIGN(SQRT(H),F)
         E(I) = SCALE * G
         H = H - F * G
         Z(I,L) = F - G
         F = 0.0
         DO 240 J = 1, L
            Z(J,I) = Z(I,J) / (SCALE * H)
            G = 0.0
            DO 180 K = 1, J
  180       G = G + Z(J,K) * Z(I,K)
            JP1 = J + 1
            IF (L .LT. JP1) GO TO 220
            DO 200 K = JP1, L
  200       G = G + Z(K,J) * Z(I,K)
  220       E(J) = G / H
            F = F + E(J) * Z(I,J)
  240    CONTINUE
         HH = F / (H + H)
         DO 260 J = 1, L
            F = Z(I,J)
            G = E(J) - HH * F
            E(J) = G
            DO 260 K = 1, J
               Z(J,K) = Z(J,K) - F * E(K) - G * Z(I,K)
  260    CONTINUE
         DO 280 K = 1, L
  280    Z(I,K) = SCALE * Z(I,K)
  290    D(I) = H
  300 CONTINUE
  320 D(1) = 0.0
      E(1) = 0.0
      DO 500 I = 1, N
         L = I - 1
         IF (D(I) .EQ. 0.0) GO TO 380
         DO 360 J = 1, L
            G = 0.0
            DO 340 K = 1, L
  340       G = G + Z(I,K) * Z(K,J)
            DO 360 K = 1, L
               Z(K,J) = Z(K,J) - G * Z(K,I)
  360    CONTINUE
  380    D(I) = Z(I,I)
         Z(I,I) = 1.0
         IF (L .LT. 1) GO TO 500
         DO 400 J = 1, L
            Z(I,J) = 0.0
            Z(J,I) = 0.0
  400    CONTINUE
  500 CONTINUE
      RETURN
      END
Commit	Line	Data
fe4da5cc	1	*
	2	* $Id$
	3	*
	4	* $Log$
	5	* Revision 1.1.1.1 1996/04/01 15:02:38 mclareni
	6	* Mathlib gen
	7	*
	8	*
	9	#include "gen/pilot.h"
	10	SUBROUTINE TRED2(NM,N,A,D,E,Z)
	11	INTEGER I,J,K,L,N,II,NM,JP1
	12	REAL A(NM,N),D(N),E(N),Z(NM,N)
	13	REAL F,G,H,HH,SCALE
	14	DO 100 I = 1, N
	15	DO 100 J = 1, I
	16	Z(I,J) = A(I,J)
	17	100 CONTINUE
	18	IF (N .EQ. 1) GO TO 320
	19	DO 300 II = 2, N
	20	I = N + 2 - II
	21	L = I - 1
	22	H = 0.0
	23	SCALE = 0.0
	24	IF (L .LT. 2) GO TO 130
	25	DO 120 K = 1, L
	26	120 SCALE = SCALE + ABS(Z(I,K))
	27	IF (SCALE .NE. 0.0) GO TO 140
	28	130 E(I) = Z(I,L)
	29	GO TO 290
	30	140 DO 150 K = 1, L
	31	Z(I,K) = Z(I,K) / SCALE
	32	H = H + Z(I,K) * Z(I,K)
	33	150 CONTINUE
	34	F = Z(I,L)
	35	G = -SIGN(SQRT(H),F)
	36	E(I) = SCALE * G
	37	H = H - F * G
	38	Z(I,L) = F - G
	39	F = 0.0
	40	DO 240 J = 1, L
	41	Z(J,I) = Z(I,J) / (SCALE * H)
	42	G = 0.0
	43	DO 180 K = 1, J
	44	180 G = G + Z(J,K) * Z(I,K)
	45	JP1 = J + 1
	46	IF (L .LT. JP1) GO TO 220
	47	DO 200 K = JP1, L
	48	200 G = G + Z(K,J) * Z(I,K)
	49	220 E(J) = G / H
	50	F = F + E(J) * Z(I,J)
	51	240 CONTINUE
	52	HH = F / (H + H)
	53	DO 260 J = 1, L
	54	F = Z(I,J)
	55	G = E(J) - HH * F
	56	E(J) = G
	57	DO 260 K = 1, J
	58	Z(J,K) = Z(J,K) - F * E(K) - G * Z(I,K)
	59	260 CONTINUE
	60	DO 280 K = 1, L
	61	280 Z(I,K) = SCALE * Z(I,K)
	62	290 D(I) = H
	63	300 CONTINUE
	64	320 D(1) = 0.0
65	E(1) = 0.0
66	DO 500 I = 1, N
67	L = I - 1
68	IF (D(I) .EQ. 0.0) GO TO 380
69	DO 360 J = 1, L
70	G = 0.0
71	DO 340 K = 1, L
72	340 G = G + Z(I,K) * Z(K,J)
73	DO 360 K = 1, L
74	Z(K,J) = Z(K,J) - G * Z(K,I)
75	360 CONTINUE
76	380 D(I) = Z(I,I)
77	Z(I,I) = 1.0
78	IF (L .LT. 1) GO TO 500
79	DO 400 J = 1, L
80	Z(I,J) = 0.0
81	Z(J,I) = 0.0
82	400 CONTINUE
83	500 CONTINUE
84	RETURN
85	END