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C
C***********************************************************************
C
SUBROUTINE DLABAX(N, NBAND, A, X, Y)
C
C THIS SUBROUTINE SETS Y = A*X
C WHERE X AND Y ARE VECTORS OF LENGTH N
C AND A IS AN N X NBAND SYMMETRIC BAND MATRIX
C
C FORMAL PARAMETERS
C
INTEGER N, NBAND
DOUBLE PRECISION A(NBAND,1), X(1), Y(1)
C
C LOCAL VARIABLES
C
INTEGER I, K, L, M
DOUBLE PRECISION ZERO(1)
C
C FUNCTIONS CALLED
C
INTEGER MIN0
C
C SUBROUTINES CALLED
C
C DCOPY
C
ZERO(1) = 0.0D0
CALL DCOPY(N, ZERO, 0, Y, 1)
DO 20 K = 1, N
Y(K) = Y(K) + A(1,K)*X(K)
M = MIN0(N-K+1, NBAND)
IF(M .LT. 2) GO TO 20
DO 10 I = 2, M
L = K + I - 1
Y(L) = Y(L) + A(I,K)*X(K)
Y(K) = Y(K) + A(I,K)*X(L)
10 CONTINUE
20 CONTINUE
RETURN
END
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