From d54fe7c1f704a63824c5bfa0ece65245572e9b27 Mon Sep 17 00:00:00 2001 From: Joseph Hunkeler Date: Wed, 4 Mar 2015 21:21:30 -0500 Subject: Initial commit --- src/slalib/sun67.htx/node61.html | 152 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 152 insertions(+) create mode 100644 src/slalib/sun67.htx/node61.html (limited to 'src/slalib/sun67.htx/node61.html') diff --git a/src/slalib/sun67.htx/node61.html b/src/slalib/sun67.htx/node61.html new file mode 100644 index 0000000..b72e3ac --- /dev/null +++ b/src/slalib/sun67.htx/node61.html @@ -0,0 +1,152 @@ + + + + +SLA_DMAT - Solve Simultaneous Equations + + + + + + + + + + + + +
+ +next + +up + +previous +
+ Next: SLA_DMOON - Approx Moon Pos/Vel +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_DM2AV - Rotation Matrix to Axial Vector +

+

+

SLA_DMAT - Solve Simultaneous Equations +   +

+
+
ACTION: +
Matrix inversion and solution of simultaneous equations +(double precision). +

CALL: +
CALL sla_DMAT (N, A, Y, D, JF, IW) +

+

+
GIVEN: +
+
+ + + + + + + + + + + + + +
NInumber of unknowns
AD(N,N)matrix
YD(N)vector
+

+
RETURNED: +
+
+ + + + + + + + + + + + + + + + + + + + + +
AD(N,N)matrix inverse
YD(N)solution
DDdeterminant
JFIsingularity flag: 0=OK
IWI(N)workspace
+

+
NOTES: +
+
1. +
For the set of n simultaneous linear equations in n unknowns: +
A$\cdot$y = x +
+ where: +
    +
  • A is a non-singular $n \times n$ matrix, +
  • y is the vector of n unknowns, and +
  • x is the known vector, +
+ sla_DMAT computes: +
    +
  • the inverse of matrix A, +
  • the determinant of matrix A, and +
  • the vector of n unknowns y. +
+ Argument N is the order n, A (given) is the matrix A, + Y (given) is the vector x and Y (returned) + is the vector y. + The argument A (returned) is the inverse matrix A-1, + and D is det(A). +
2. +
JF is the singularity flag. If the matrix is non-singular, + JF=0 is returned. If the matrix is singular, JF=-1 + and D=0D0 are returned. In the latter case, the contents + of array A on return are undefined. +
3. +
The algorithm is Gaussian elimination with partial pivoting. + This method is very fast; some much slower algorithms can give + better accuracy, but only by a small factor. +
4. +
This routine replaces the obsolete sla_DMATRX. +
+
+ +next + +up + +previous +
+ Next: SLA_DMOON - Approx Moon Pos/Vel +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_DM2AV - Rotation Matrix to Axial Vector +

+

+

+SLALIB --- Positional Astronomy Library
Starlink User Note 67
P. T. Wallace
12 October 1999
E-mail:ptw@star.rl.ac.uk +
+ + -- cgit