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CentOS 7.0 - man page for dlae2 (centos section 3)

dlae2.f(3)							      LAPACK								dlae2.f(3)

NAME
dlae2.f -
SYNOPSIS
Functions/Subroutines subroutine dlae2 (A, B, C, RT1, RT2) DLAE2 computes the eigenvalues of a 2-by-2 symmetric matrix. Function/Subroutine Documentation subroutine dlae2 (double precisionA, double precisionB, double precisionC, double precisionRT1, double precisionRT2) DLAE2 computes the eigenvalues of a 2-by-2 symmetric matrix. Purpose: DLAE2 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. Parameters: A A is DOUBLE PRECISION The (1,1) element of the 2-by-2 matrix. B B is DOUBLE PRECISION The (1,2) and (2,1) elements of the 2-by-2 matrix. C C is DOUBLE PRECISION The (2,2) element of the 2-by-2 matrix. RT1 RT1 is DOUBLE PRECISION The eigenvalue of larger absolute value. RT2 RT2 is DOUBLE PRECISION The eigenvalue of smaller absolute value. Author: Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Date: September 2012 Further Details: 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. Definition at line 103 of file dlae2.f. Author Generated automatically by Doxygen for LAPACK from the source code. Version 3.4.2 Tue Sep 25 2012 dlae2.f(3)