.TH "slae2.f" 3 "Wed Oct 15 2014" "Version 3.4.2" "LAPACK" \" -*- nroff -*- .ad l .nh .SH NAME slae2.f \- .SH SYNOPSIS .br .PP .SS "Functions/Subroutines" .in +1c .ti -1c .RI "subroutine \fBslae2\fP (A, B, C, RT1, RT2)" .br .RI "\fI\fBSLAE2\fP computes the eigenvalues of a 2-by-2 symmetric matrix\&. \fP" .in -1c .SH "Function/Subroutine Documentation" .PP .SS "subroutine slae2 (realA, realB, realC, realRT1, realRT2)" .PP \fBSLAE2\fP computes the eigenvalues of a 2-by-2 symmetric matrix\&. .PP \fBPurpose: \fP .RS 4 .PP .nf SLAE2 computes the eigenvalues of a 2-by-2 symmetric matrix [ A B ] [ B C ]. On return, RT1 is the eigenvalue of larger absolute value, and RT2 is the eigenvalue of smaller absolute value. .fi .PP .RE .PP \fBParameters:\fP .RS 4 \fIA\fP .PP .nf A is REAL The (1,1) element of the 2-by-2 matrix. .fi .PP .br \fIB\fP .PP .nf B is REAL The (1,2) and (2,1) elements of the 2-by-2 matrix. .fi .PP .br \fIC\fP .PP .nf C is REAL The (2,2) element of the 2-by-2 matrix. .fi .PP .br \fIRT1\fP .PP .nf RT1 is REAL The eigenvalue of larger absolute value. .fi .PP .br \fIRT2\fP .PP .nf RT2 is REAL The eigenvalue of smaller absolute value. .fi .PP .RE .PP \fBAuthor:\fP .RS 4 Univ\&. of Tennessee .PP Univ\&. of California Berkeley .PP Univ\&. of Colorado Denver .PP NAG Ltd\&. .RE .PP \fBDate:\fP .RS 4 September 2012 .RE .PP \fBFurther Details: \fP .RS 4 .PP .nf RT1 is accurate to a few ulps barring over/underflow. RT2 may be inaccurate if there is massive cancellation in the determinant A*C-B*B; higher precision or correctly rounded or correctly truncated arithmetic would be needed to compute RT2 accurately in all cases. Overflow is possible only if RT1 is within a factor of 5 of overflow. Underflow is harmless if the input data is 0 or exceeds underflow_threshold / macheps. .fi .PP .RE .PP .PP Definition at line 103 of file slae2\&.f\&. .SH "Author" .PP Generated automatically by Doxygen for LAPACK from the source code\&.