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   1:  #region Translated by Jose Antonio De Santiago-Castillo.
   2:   
   3:  //Translated by Jose Antonio De Santiago-Castillo. 
   4:  //E-mail:JAntonioDeSantiago@gmail.com
   5:  //Web: www.DotNumerics.com
   6:  //
   7:  //Fortran to C# Translation.
   8:  //Translated by:
   9:  //F2CSharp Version 0.71 (November 10, 2009)
  10:  //Code Optimizations: None
  11:  //
  12:  #endregion
  13:   
  14:  using System;
  15:  using DotNumerics.FortranLibrary;
  16:   
  17:  namespace DotNumerics.CSLapack
  18:  {
  19:      /// <summary>
  20:      /// -- LAPACK routine (version 3.1) --
  21:      /// Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
  22:      /// November 2006
  23:      /// Purpose
  24:      /// =======
  25:      /// 
  26:      /// DGELQ2 computes an LQ factorization of a real m by n matrix A:
  27:      /// A = L * Q.
  28:      /// 
  29:      ///</summary>
  30:      public class DGELQ2
  31:      {
  32:      
  33:   
  34:          #region Dependencies
  35:          
  36:          DLARF _dlarf; DLARFG _dlarfg; XERBLA _xerbla; 
  37:   
  38:          #endregion
  39:   
  40:   
  41:          #region Fields
  42:          
  43:          const double ONE = 1.0E+0; int I = 0; int K = 0; double AII = 0; 
  44:   
  45:          #endregion
  46:   
  47:          public DGELQ2(DLARF dlarf, DLARFG dlarfg, XERBLA xerbla)
  48:          {
  49:      
  50:   
  51:              #region Set Dependencies
  52:              
  53:              this._dlarf = dlarf; this._dlarfg = dlarfg; this._xerbla = xerbla; 
  54:   
  55:              #endregion
  56:   
  57:          }
  58:      
  59:          public DGELQ2()
  60:          {
  61:      
  62:   
  63:              #region Dependencies (Initialization)
  64:              
  65:              LSAME lsame = new LSAME();
  66:              XERBLA xerbla = new XERBLA();
  67:              DLAMC3 dlamc3 = new DLAMC3();
  68:              DLAPY2 dlapy2 = new DLAPY2();
  69:              DNRM2 dnrm2 = new DNRM2();
  70:              DSCAL dscal = new DSCAL();
  71:              DGEMV dgemv = new DGEMV(lsame, xerbla);
  72:              DGER dger = new DGER(xerbla);
  73:              DLARF dlarf = new DLARF(dgemv, dger, lsame);
  74:              DLAMC1 dlamc1 = new DLAMC1(dlamc3);
  75:              DLAMC4 dlamc4 = new DLAMC4(dlamc3);
  76:              DLAMC5 dlamc5 = new DLAMC5(dlamc3);
  77:              DLAMC2 dlamc2 = new DLAMC2(dlamc3, dlamc1, dlamc4, dlamc5);
  78:              DLAMCH dlamch = new DLAMCH(lsame, dlamc2);
  79:              DLARFG dlarfg = new DLARFG(dlamch, dlapy2, dnrm2, dscal);
  80:   
  81:              #endregion
  82:   
  83:   
  84:              #region Set Dependencies
  85:              
  86:              this._dlarf = dlarf; this._dlarfg = dlarfg; this._xerbla = xerbla; 
  87:   
  88:              #endregion
  89:   
  90:          }
  91:          /// <summary>
  92:          /// Purpose
  93:          /// =======
  94:          /// 
  95:          /// DGELQ2 computes an LQ factorization of a real m by n matrix A:
  96:          /// A = L * Q.
  97:          /// 
  98:          ///</summary>
  99:          /// <param name="M">
 100:          /// (input) INTEGER
 101:          /// The number of rows of the matrix A.  M .GE. 0.
 102:          ///</param>
 103:          /// <param name="N">
 104:          /// (input) INTEGER
 105:          /// The number of columns of the matrix A.  N .GE. 0.
 106:          ///</param>
 107:          /// <param name="A">
 108:          /// (input/output) DOUBLE PRECISION array, dimension (LDA,N)
 109:          /// On entry, the m by n matrix A.
 110:          /// On exit, the elements on and below the diagonal of the array
 111:          /// contain the m by min(m,n) lower trapezoidal matrix L (L is
 112:          /// lower triangular if m .LE. n); the elements above the diagonal,
 113:          /// with the array TAU, represent the orthogonal matrix Q as a
 114:          /// product of elementary reflectors (see Further Details).
 115:          ///</param>
 116:          /// <param name="LDA">
 117:          /// (input) INTEGER
 118:          /// The leading dimension of the array A.  LDA .GE. max(1,M).
 119:          ///</param>
 120:          /// <param name="TAU">
 121:          /// (output) DOUBLE PRECISION array, dimension (min(M,N))
 122:          /// The scalar factors of the elementary reflectors (see Further
 123:          /// Details).
 124:          ///</param>
 125:          /// <param name="WORK">
 126:          /// (workspace) DOUBLE PRECISION array, dimension (M)
 127:          ///</param>
 128:          /// <param name="INFO">
 129:          /// (output) INTEGER
 130:          /// = 0: successful exit
 131:          /// .LT. 0: if INFO = -i, the i-th argument had an illegal value
 132:          ///</param>
 133:          public void Run(int M, int N, ref double[] A, int offset_a, int LDA, ref double[] TAU, int offset_tau, ref double[] WORK, int offset_work
 134:                           , ref int INFO)
 135:          {
 136:   
 137:              #region Array Index Correction
 138:              
 139:               int o_a = -1 - LDA + offset_a;  int o_tau = -1 + offset_tau;  int o_work = -1 + offset_work; 
 140:   
 141:              #endregion
 142:   
 143:   
 144:              #region Prolog
 145:              
 146:              // *
 147:              // *  -- LAPACK routine (version 3.1) --
 148:              // *     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
 149:              // *     November 2006
 150:              // *
 151:              // *     .. Scalar Arguments ..
 152:              // *     ..
 153:              // *     .. Array Arguments ..
 154:              // *     ..
 155:              // *
 156:              // *  Purpose
 157:              // *  =======
 158:              // *
 159:              // *  DGELQ2 computes an LQ factorization of a real m by n matrix A:
 160:              // *  A = L * Q.
 161:              // *
 162:              // *  Arguments
 163:              // *  =========
 164:              // *
 165:              // *  M       (input) INTEGER
 166:              // *          The number of rows of the matrix A.  M >= 0.
 167:              // *
 168:              // *  N       (input) INTEGER
 169:              // *          The number of columns of the matrix A.  N >= 0.
 170:              // *
 171:              // *  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
 172:              // *          On entry, the m by n matrix A.
 173:              // *          On exit, the elements on and below the diagonal of the array
 174:              // *          contain the m by min(m,n) lower trapezoidal matrix L (L is
 175:              // *          lower triangular if m <= n); the elements above the diagonal,
 176:              // *          with the array TAU, represent the orthogonal matrix Q as a
 177:              // *          product of elementary reflectors (see Further Details).
 178:              // *
 179:              // *  LDA     (input) INTEGER
 180:              // *          The leading dimension of the array A.  LDA >= max(1,M).
 181:              // *
 182:              // *  TAU     (output) DOUBLE PRECISION array, dimension (min(M,N))
 183:              // *          The scalar factors of the elementary reflectors (see Further
 184:              // *          Details).
 185:              // *
 186:              // *  WORK    (workspace) DOUBLE PRECISION array, dimension (M)
 187:              // *
 188:              // *  INFO    (output) INTEGER
 189:              // *          = 0: successful exit
 190:              // *          < 0: if INFO = -i, the i-th argument had an illegal value
 191:              // *
 192:              // *  Further Details
 193:              // *  ===============
 194:              // *
 195:              // *  The matrix Q is represented as a product of elementary reflectors
 196:              // *
 197:              // *     Q = H(k) . . . H(2) H(1), where k = min(m,n).
 198:              // *
 199:              // *  Each H(i) has the form
 200:              // *
 201:              // *     H(i) = I - tau * v * v'
 202:              // *
 203:              // *  where tau is a real scalar, and v is a real vector with
 204:              // *  v(1:i-1) = 0 and v(i) = 1; v(i+1:n) is stored on exit in A(i,i+1:n),
 205:              // *  and tau in TAU(i).
 206:              // *
 207:              // *  =====================================================================
 208:              // *
 209:              // *     .. Parameters ..
 210:              // *     ..
 211:              // *     .. Local Scalars ..
 212:              // *     ..
 213:              // *     .. External Subroutines ..
 214:              // *     ..
 215:              // *     .. Intrinsic Functions ..
 216:              //      INTRINSIC          MAX, MIN;
 217:              // *     ..
 218:              // *     .. Executable Statements ..
 219:              // *
 220:              // *     Test the input arguments
 221:              // *
 222:   
 223:              #endregion
 224:   
 225:   
 226:              #region Body
 227:              
 228:              INFO = 0;
 229:              if (M < 0)
 230:              {
 231:                  INFO =  - 1;
 232:              }
 233:              else
 234:              {
 235:                  if (N < 0)
 236:                  {
 237:                      INFO =  - 2;
 238:                  }
 239:                  else
 240:                  {
 241:                      if (LDA < Math.Max(1, M))
 242:                      {
 243:                          INFO =  - 4;
 244:                      }
 245:                  }
 246:              }
 247:              if (INFO != 0)
 248:              {
 249:                  this._xerbla.Run("DGELQ2",  - INFO);
 250:                  return;
 251:              }
 252:              // *
 253:              K = Math.Min(M, N);
 254:              // *
 255:              for (I = 1; I <= K; I++)
 256:              {
 257:                  // *
 258:                  // *        Generate elementary reflector H(i) to annihilate A(i,i+1:n)
 259:                  // *
 260:                  this._dlarfg.Run(N - I + 1, ref A[I+I * LDA + o_a], ref A, I+Math.Min(I + 1, N) * LDA + o_a, LDA, ref TAU[I + o_tau]);
 261:                  if (I < M)
 262:                  {
 263:                      // *
 264:                      // *           Apply H(i) to A(i+1:m,i:n) from the right
 265:                      // *
 266:                      AII = A[I+I * LDA + o_a];
 267:                      A[I+I * LDA + o_a] = ONE;
 268:                      this._dlarf.Run("Right", M - I, N - I + 1, A, I+I * LDA + o_a, LDA, TAU[I + o_tau]
 269:                                      , ref A, I + 1+I * LDA + o_a, LDA, ref WORK, offset_work);
 270:                      A[I+I * LDA + o_a] = AII;
 271:                  }
 272:              }
 273:              return;
 274:              // *
 275:              // *     End of DGELQ2
 276:              // *
 277:   
 278:              #endregion
 279:   
 280:          }
 281:      }
 282:  }