zgerq2.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 148 行

HTML
148 行
字号 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
 <head>
  <title>zgerq2.f</title>
 <meta name="generator" content="emacs 21.3.1; htmlfontify 0.20">
<style type="text/css"><!-- 
body { background: rgb(255, 255, 255);  color: rgb(0, 0, 0);  font-style: normal;  font-weight: 500;  font-stretch: normal;  font-family: adobe-courier;  font-size: 11pt;  text-decoration: none; }
span.default   { background: rgb(255, 255, 255);  color: rgb(0, 0, 0);  font-style: normal;  font-weight: 500;  font-stretch: normal;  font-family: adobe-courier;  font-size: 11pt;  text-decoration: none; }
span.default a { background: rgb(255, 255, 255);  color: rgb(0, 0, 0);  font-style: normal;  font-weight: 500;  font-stretch: normal;  font-family: adobe-courier;  font-size: 11pt;  text-decoration: underline; }
span.string   { color: rgb(188, 143, 143);  background: rgb(255, 255, 255);  font-style: normal;  font-weight: 500;  font-stretch: normal;  font-family: adobe-courier;  font-size: 11pt;  text-decoration: none; }
span.string a { color: rgb(188, 143, 143);  background: rgb(255, 255, 255);  font-style: normal;  font-weight: 500;  font-stretch: normal;  font-family: adobe-courier;  font-size: 11pt;  text-decoration: underline; }
span.comment   { color: rgb(178, 34, 34);  background: rgb(255, 255, 255);  font-style: normal;  font-weight: 500;  font-stretch: normal;  font-family: adobe-courier;  font-size: 11pt;  text-decoration: none; }
span.comment a { color: rgb(178, 34, 34);  background: rgb(255, 255, 255);  font-style: normal;  font-weight: 500;  font-stretch: normal;  font-family: adobe-courier;  font-size: 11pt;  text-decoration: underline; }
 --></style>

 </head>
  <body>

<pre>
      SUBROUTINE <a name="ZGERQ2.1"></a><a href="zgerq2.f.html#ZGERQ2.1">ZGERQ2</a>( M, N, A, LDA, TAU, WORK, INFO )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  -- LAPACK routine (version 3.1) --
</span><span class="comment">*</span><span class="comment">     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
</span><span class="comment">*</span><span class="comment">     November 2006
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     .. Scalar Arguments ..
</span>      INTEGER            INFO, LDA, M, N
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Array Arguments ..
</span>      COMPLEX*16         A( LDA, * ), TAU( * ), WORK( * )
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  Purpose
</span><span class="comment">*</span><span class="comment">  =======
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  <a name="ZGERQ2.17"></a><a href="zgerq2.f.html#ZGERQ2.1">ZGERQ2</a> computes an RQ factorization of a complex m by n matrix A:
</span><span class="comment">*</span><span class="comment">  A = R * Q.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  Arguments
</span><span class="comment">*</span><span class="comment">  =========
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  M       (input) INTEGER
</span><span class="comment">*</span><span class="comment">          The number of rows of the matrix A.  M &gt;= 0.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  N       (input) INTEGER
</span><span class="comment">*</span><span class="comment">          The number of columns of the matrix A.  N &gt;= 0.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  A       (input/output) COMPLEX*16 array, dimension (LDA,N)
</span><span class="comment">*</span><span class="comment">          On entry, the m by n matrix A.
</span><span class="comment">*</span><span class="comment">          On exit, if m &lt;= n, the upper triangle of the subarray
</span><span class="comment">*</span><span class="comment">          A(1:m,n-m+1:n) contains the m by m upper triangular matrix R;
</span><span class="comment">*</span><span class="comment">          if m &gt;= n, the elements on and above the (m-n)-th subdiagonal
</span><span class="comment">*</span><span class="comment">          contain the m by n upper trapezoidal matrix R; the remaining
</span><span class="comment">*</span><span class="comment">          elements, with the array TAU, represent the unitary matrix
</span><span class="comment">*</span><span class="comment">          Q as a product of elementary reflectors (see Further
</span><span class="comment">*</span><span class="comment">          Details).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  LDA     (input) INTEGER
</span><span class="comment">*</span><span class="comment">          The leading dimension of the array A.  LDA &gt;= max(1,M).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  TAU     (output) COMPLEX*16 array, dimension (min(M,N))
</span><span class="comment">*</span><span class="comment">          The scalar factors of the elementary reflectors (see Further
</span><span class="comment">*</span><span class="comment">          Details).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  WORK    (workspace) COMPLEX*16 array, dimension (M)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  INFO    (output) INTEGER
</span><span class="comment">*</span><span class="comment">          = 0: successful exit
</span><span class="comment">*</span><span class="comment">          &lt; 0: if INFO = -i, the i-th argument had an illegal value
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  Further Details
</span><span class="comment">*</span><span class="comment">  ===============
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  The matrix Q is represented as a product of elementary reflectors
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Q = H(1)' H(2)' . . . H(k)', where k = min(m,n).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  Each H(i) has the form
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     H(i) = I - tau * v * v'
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  where tau is a complex scalar, and v is a complex vector with
</span><span class="comment">*</span><span class="comment">  v(n-k+i+1:n) = 0 and v(n-k+i) = 1; conjg(v(1:n-k+i-1)) is stored on
</span><span class="comment">*</span><span class="comment">  exit in A(m-k+i,1:n-k+i-1), and tau in TAU(i).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  =====================================================================
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     .. Parameters ..
</span>      COMPLEX*16         ONE
      PARAMETER          ( ONE = ( 1.0D+0, 0.0D+0 ) )
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Local Scalars ..
</span>      INTEGER            I, K
      COMPLEX*16         ALPHA
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Subroutines ..
</span>      EXTERNAL           <a name="XERBLA.78"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>, <a name="ZLACGV.78"></a><a href="zlacgv.f.html#ZLACGV.1">ZLACGV</a>, <a name="ZLARF.78"></a><a href="zlarf.f.html#ZLARF.1">ZLARF</a>, <a name="ZLARFG.78"></a><a href="zlarfg.f.html#ZLARFG.1">ZLARFG</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Intrinsic Functions ..
</span>      INTRINSIC          MAX, MIN
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Executable Statements ..
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Test the input arguments
</span><span class="comment">*</span><span class="comment">
</span>      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.96"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="ZGERQ2.96"></a><a href="zgerq2.f.html#ZGERQ2.1">ZGERQ2</a>'</span>, -INFO )
         RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span>      K = MIN( M, N )
<span class="comment">*</span><span class="comment">
</span>      DO 10 I = K, 1, -1
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Generate elementary reflector H(i) to annihilate
</span><span class="comment">*</span><span class="comment">        A(m-k+i,1:n-k+i-1)
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="ZLACGV.107"></a><a href="zlacgv.f.html#ZLACGV.1">ZLACGV</a>( N-K+I, A( M-K+I, 1 ), LDA )
         ALPHA = A( M-K+I, N-K+I )
         CALL <a name="ZLARFG.109"></a><a href="zlarfg.f.html#ZLARFG.1">ZLARFG</a>( N-K+I, ALPHA, A( M-K+I, 1 ), LDA, TAU( I ) )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Apply H(i) to A(1:m-k+i-1,1:n-k+i) from the right
</span><span class="comment">*</span><span class="comment">
</span>         A( M-K+I, N-K+I ) = ONE
         CALL <a name="ZLARF.114"></a><a href="zlarf.f.html#ZLARF.1">ZLARF</a>( <span class="string">'Right'</span>, M-K+I-1, N-K+I, A( M-K+I, 1 ), LDA,
     $               TAU( I ), A, LDA, WORK )
         A( M-K+I, N-K+I ) = ALPHA
         CALL <a name="ZLACGV.117"></a><a href="zlacgv.f.html#ZLACGV.1">ZLACGV</a>( N-K+I-1, A( M-K+I, 1 ), LDA )
   10 CONTINUE
      RETURN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     End of <a name="ZGERQ2.121"></a><a href="zgerq2.f.html#ZGERQ2.1">ZGERQ2</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

</pre>

 </body>
</html>

zgerq2.f.html - 源码说明

本页面展示了「famous linear algebra library (LAPACK) ports to windows」中的 zgerq2.f.html 源码文件，采用 HTML 编程语言编写，共 148 行代码。您可以在线阅读完整代码内容，也可以返回资源详情页下载完整源码包进行本地学习和开发。

虫虫下载站收录了大量与algebra相关的技术资源，包括源代码、技术文档、电路图等，是电子工程师和嵌入式开发者的专业学习平台。

⌨️ 快捷键说明

复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?