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LAPACK 3.3.0
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LAPACK 3.3.0
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00001 SUBROUTINE DLAR2V( N, X, Y, Z, INCX, C, S, INCC ) 00002 * 00003 * -- LAPACK auxiliary routine (version 3.2) -- 00004 * -- LAPACK is a software package provided by Univ. of Tennessee, -- 00005 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- 00006 * November 2006 00007 * 00008 * .. Scalar Arguments .. 00009 INTEGER INCC, INCX, N 00010 * .. 00011 * .. Array Arguments .. 00012 DOUBLE PRECISION C( * ), S( * ), X( * ), Y( * ), Z( * ) 00013 * .. 00014 * 00015 * Purpose 00016 * ======= 00017 * 00018 * DLAR2V applies a vector of real plane rotations from both sides to 00019 * a sequence of 2-by-2 real symmetric matrices, defined by the elements 00020 * of the vectors x, y and z. For i = 1,2,...,n 00021 * 00022 * ( x(i) z(i) ) := ( c(i) s(i) ) ( x(i) z(i) ) ( c(i) -s(i) ) 00023 * ( z(i) y(i) ) ( -s(i) c(i) ) ( z(i) y(i) ) ( s(i) c(i) ) 00024 * 00025 * Arguments 00026 * ========= 00027 * 00028 * N (input) INTEGER 00029 * The number of plane rotations to be applied. 00030 * 00031 * X (input/output) DOUBLE PRECISION array, 00032 * dimension (1+(N-1)*INCX) 00033 * The vector x. 00034 * 00035 * Y (input/output) DOUBLE PRECISION array, 00036 * dimension (1+(N-1)*INCX) 00037 * The vector y. 00038 * 00039 * Z (input/output) DOUBLE PRECISION array, 00040 * dimension (1+(N-1)*INCX) 00041 * The vector z. 00042 * 00043 * INCX (input) INTEGER 00044 * The increment between elements of X, Y and Z. INCX > 0. 00045 * 00046 * C (input) DOUBLE PRECISION array, dimension (1+(N-1)*INCC) 00047 * The cosines of the plane rotations. 00048 * 00049 * S (input) DOUBLE PRECISION array, dimension (1+(N-1)*INCC) 00050 * The sines of the plane rotations. 00051 * 00052 * INCC (input) INTEGER 00053 * The increment between elements of C and S. INCC > 0. 00054 * 00055 * ===================================================================== 00056 * 00057 * .. Local Scalars .. 00058 INTEGER I, IC, IX 00059 DOUBLE PRECISION CI, SI, T1, T2, T3, T4, T5, T6, XI, YI, ZI 00060 * .. 00061 * .. Executable Statements .. 00062 * 00063 IX = 1 00064 IC = 1 00065 DO 10 I = 1, N 00066 XI = X( IX ) 00067 YI = Y( IX ) 00068 ZI = Z( IX ) 00069 CI = C( IC ) 00070 SI = S( IC ) 00071 T1 = SI*ZI 00072 T2 = CI*ZI 00073 T3 = T2 - SI*XI 00074 T4 = T2 + SI*YI 00075 T5 = CI*XI + T1 00076 T6 = CI*YI - T1 00077 X( IX ) = CI*T5 + SI*T4 00078 Y( IX ) = CI*T6 - SI*T3 00079 Z( IX ) = CI*T4 - SI*T5 00080 IX = IX + INCX 00081 IC = IC + INCC 00082 10 CONTINUE 00083 * 00084 * End of DLAR2V 00085 * 00086 RETURN 00087 END
1.7.3 
