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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:      /// DORG2L generates an m by n real matrix Q with orthonormal columns,
  27:      /// which is defined as the last n columns of a product of k elementary
  28:      /// reflectors of order m
  29:      /// 
  30:      /// Q  =  H(k) . . . H(2) H(1)
  31:      /// 
  32:      /// as returned by DGEQLF.
  33:      /// 
  34:      ///</summary>
  35:      public class DORG2L
  36:      {
  37:      
  38:   
  39:          #region Dependencies
  40:          
  41:          DLARF _dlarf; DSCAL _dscal; XERBLA _xerbla; 
  42:   
  43:          #endregion
  44:   
  45:   
  46:          #region Fields
  47:          
  48:          const double ONE = 1.0E+0; const double ZERO = 0.0E+0; int I = 0; int II = 0; int J = 0; int L = 0; 
  49:   
  50:          #endregion
  51:   
  52:          public DORG2L(DLARF dlarf, DSCAL dscal, XERBLA xerbla)
  53:          {
  54:      
  55:   
  56:              #region Set Dependencies
  57:              
  58:              this._dlarf = dlarf; this._dscal = dscal; this._xerbla = xerbla; 
  59:   
  60:              #endregion
  61:   
  62:          }
  63:      
  64:          public DORG2L()
  65:          {
  66:      
  67:   
  68:              #region Dependencies (Initialization)
  69:              
  70:              LSAME lsame = new LSAME();
  71:              XERBLA xerbla = new XERBLA();
  72:              DSCAL dscal = new DSCAL();
  73:              DGEMV dgemv = new DGEMV(lsame, xerbla);
  74:              DGER dger = new DGER(xerbla);
  75:              DLARF dlarf = new DLARF(dgemv, dger, lsame);
  76:   
  77:              #endregion
  78:   
  79:   
  80:              #region Set Dependencies
  81:              
  82:              this._dlarf = dlarf; this._dscal = dscal; this._xerbla = xerbla; 
  83:   
  84:              #endregion
  85:   
  86:          }
  87:          /// <summary>
  88:          /// Purpose
  89:          /// =======
  90:          /// 
  91:          /// DORG2L generates an m by n real matrix Q with orthonormal columns,
  92:          /// which is defined as the last n columns of a product of k elementary
  93:          /// reflectors of order m
  94:          /// 
  95:          /// Q  =  H(k) . . . H(2) H(1)
  96:          /// 
  97:          /// as returned by DGEQLF.
  98:          /// 
  99:          ///</summary>
 100:          /// <param name="M">
 101:          /// (input) INTEGER
 102:          /// The number of rows of the matrix Q. M .GE. 0.
 103:          ///</param>
 104:          /// <param name="N">
 105:          /// (input) INTEGER
 106:          /// The number of columns of the matrix Q. M .GE. N .GE. 0.
 107:          ///</param>
 108:          /// <param name="K">
 109:          /// (input) INTEGER
 110:          /// The number of elementary reflectors whose product defines the
 111:          /// matrix Q. N .GE. K .GE. 0.
 112:          ///</param>
 113:          /// <param name="A">
 114:          /// (input/output) DOUBLE PRECISION array, dimension (LDA,N)
 115:          /// On entry, the (n-k+i)-th column must contain the vector which
 116:          /// defines the elementary reflector H(i), for i = 1,2,...,k, as
 117:          /// returned by DGEQLF in the last k columns of its array
 118:          /// argument A.
 119:          /// On exit, the m by n matrix Q.
 120:          ///</param>
 121:          /// <param name="LDA">
 122:          /// (input) INTEGER
 123:          /// The first dimension of the array A. LDA .GE. max(1,M).
 124:          ///</param>
 125:          /// <param name="TAU">
 126:          /// (input) DOUBLE PRECISION array, dimension (K)
 127:          /// TAU(i) must contain the scalar factor of the elementary
 128:          /// reflector H(i), as returned by DGEQLF.
 129:          ///</param>
 130:          /// <param name="WORK">
 131:          /// (workspace) DOUBLE PRECISION array, dimension (N)
 132:          ///</param>
 133:          /// <param name="INFO">
 134:          /// (output) INTEGER
 135:          /// = 0: successful exit
 136:          /// .LT. 0: if INFO = -i, the i-th argument has an illegal value
 137:          ///</param>
 138:          public void Run(int M, int N, int K, ref double[] A, int offset_a, int LDA, double[] TAU, int offset_tau
 139:                           , ref double[] WORK, int offset_work, ref int INFO)
 140:          {
 141:   
 142:              #region Array Index Correction
 143:              
 144:               int o_a = -1 - LDA + offset_a;  int o_tau = -1 + offset_tau;  int o_work = -1 + offset_work; 
 145:   
 146:              #endregion
 147:   
 148:   
 149:              #region Prolog
 150:              
 151:              // *
 152:              // *  -- LAPACK routine (version 3.1) --
 153:              // *     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
 154:              // *     November 2006
 155:              // *
 156:              // *     .. Scalar Arguments ..
 157:              // *     ..
 158:              // *     .. Array Arguments ..
 159:              // *     ..
 160:              // *
 161:              // *  Purpose
 162:              // *  =======
 163:              // *
 164:              // *  DORG2L generates an m by n real matrix Q with orthonormal columns,
 165:              // *  which is defined as the last n columns of a product of k elementary
 166:              // *  reflectors of order m
 167:              // *
 168:              // *        Q  =  H(k) . . . H(2) H(1)
 169:              // *
 170:              // *  as returned by DGEQLF.
 171:              // *
 172:              // *  Arguments
 173:              // *  =========
 174:              // *
 175:              // *  M       (input) INTEGER
 176:              // *          The number of rows of the matrix Q. M >= 0.
 177:              // *
 178:              // *  N       (input) INTEGER
 179:              // *          The number of columns of the matrix Q. M >= N >= 0.
 180:              // *
 181:              // *  K       (input) INTEGER
 182:              // *          The number of elementary reflectors whose product defines the
 183:              // *          matrix Q. N >= K >= 0.
 184:              // *
 185:              // *  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
 186:              // *          On entry, the (n-k+i)-th column must contain the vector which
 187:              // *          defines the elementary reflector H(i), for i = 1,2,...,k, as
 188:              // *          returned by DGEQLF in the last k columns of its array
 189:              // *          argument A.
 190:              // *          On exit, the m by n matrix Q.
 191:              // *
 192:              // *  LDA     (input) INTEGER
 193:              // *          The first dimension of the array A. LDA >= max(1,M).
 194:              // *
 195:              // *  TAU     (input) DOUBLE PRECISION array, dimension (K)
 196:              // *          TAU(i) must contain the scalar factor of the elementary
 197:              // *          reflector H(i), as returned by DGEQLF.
 198:              // *
 199:              // *  WORK    (workspace) DOUBLE PRECISION array, dimension (N)
 200:              // *
 201:              // *  INFO    (output) INTEGER
 202:              // *          = 0: successful exit
 203:              // *          < 0: if INFO = -i, the i-th argument has an illegal value
 204:              // *
 205:              // *  =====================================================================
 206:              // *
 207:              // *     .. Parameters ..
 208:              // *     ..
 209:              // *     .. Local Scalars ..
 210:              // *     ..
 211:              // *     .. External Subroutines ..
 212:              // *     ..
 213:              // *     .. Intrinsic Functions ..
 214:              //      INTRINSIC          MAX;
 215:              // *     ..
 216:              // *     .. Executable Statements ..
 217:              // *
 218:              // *     Test the input arguments
 219:              // *
 220:   
 221:              #endregion
 222:   
 223:   
 224:              #region Body
 225:              
 226:              INFO = 0;
 227:              if (M < 0)
 228:              {
 229:                  INFO =  - 1;
 230:              }
 231:              else
 232:              {
 233:                  if (N < 0 || N > M)
 234:                  {
 235:                      INFO =  - 2;
 236:                  }
 237:                  else
 238:                  {
 239:                      if (K < 0 || K > N)
 240:                      {
 241:                          INFO =  - 3;
 242:                      }
 243:                      else
 244:                      {
 245:                          if (LDA < Math.Max(1, M))
 246:                          {
 247:                              INFO =  - 5;
 248:                          }
 249:                      }
 250:                  }
 251:              }
 252:              if (INFO != 0)
 253:              {
 254:                  this._xerbla.Run("DORG2L",  - INFO);
 255:                  return;
 256:              }
 257:              // *
 258:              // *     Quick return if possible
 259:              // *
 260:              if (N <= 0) return;
 261:              // *
 262:              // *     Initialise columns 1:n-k to columns of the unit matrix
 263:              // *
 264:              for (J = 1; J <= N - K; J++)
 265:              {
 266:                  for (L = 1; L <= M; L++)
 267:                  {
 268:                      A[L+J * LDA + o_a] = ZERO;
 269:                  }
 270:                  A[M - N + J+J * LDA + o_a] = ONE;
 271:              }
 272:              // *
 273:              for (I = 1; I <= K; I++)
 274:              {
 275:                  II = N - K + I;
 276:                  // *
 277:                  // *        Apply H(i) to A(1:m-k+i,1:n-k+i) from the left
 278:                  // *
 279:                  A[M - N + II+II * LDA + o_a] = ONE;
 280:                  this._dlarf.Run("Left", M - N + II, II - 1, A, 1+II * LDA + o_a, 1, TAU[I + o_tau]
 281:                                  , ref A, offset_a, LDA, ref WORK, offset_work);
 282:                  this._dscal.Run(M - N + II - 1,  - TAU[I + o_tau], ref A, 1+II * LDA + o_a, 1);
 283:                  A[M - N + II+II * LDA + o_a] = ONE - TAU[I + o_tau];
 284:                  // *
 285:                  // *        Set A(m-k+i+1:m,n-k+i) to zero
 286:                  // *
 287:                  for (L = M - N + II + 1; L <= M; L++)
 288:                  {
 289:                      A[L+II * LDA + o_a] = ZERO;
 290:                  }
 291:              }
 292:              return;
 293:              // *
 294:              // *     End of DORG2L
 295:              // *
 296:   
 297:              #endregion
 298:   
 299:          }
 300:      }
 301:  }