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A subroutine naming convention is employed in which each subroutine
name is a coded specification of the computation done by that
subroutine. All names consist of five letter in the form TXXYY. The
first letter, T, indicates the matrix data type. Standard FORTRAN
allows the use of three such types:
S REAL
D DOUBLE PRECISION
C COMPLEX
In addition, some FORTRAN systems (alas, NOT the DEC-20!) allow a
double precision complex type:
Z COMPLEX*16
The next two letters, XX, indicate the form of the matrix or its
decomposition:
CH Cholesky decomposition
GB General band
GE General
GT General tridiagonal
HI Hermitian indefinite
HP Hermitian indefinite packed
PB Positive definite band
PO Positive definite
PP Positive definite packed
PT Positive definite tridiagonal
QR Orthogonal-triangular decomposition
SI Symmetric indefinite
SP Symmetric indefinite packed
SV Singular value decomposition
TR Triangular
The final two letters, YY, indicate the computation done by a
particular subroutine:
CO Factor and estimate condition
DC Decompose
DD Downdate
DI Determinant and/or inverse and/or inertia
EX Exchange
FA Factor
SL Solve
UD Update
The following chart shows all the LINPACK subroutine. The initial S in
the names may be replaced by D, C, or Z, and the initial C in the
complex-only names may be replaced by a Z.
CO FA SL DI
SGE * * * *
SGB * * * *
SPO * * * *
SPP * * * *
SPB * * * *
SSI * * * *
SSP * * * *
CHI * * * *
CHP * * * *
STR * * *
SGT *
SPT *
DC SL UD DD EX
SCH * * * *
SQR * *
SSV *