Purpose
To compute the coefficients c and s (c^2 + s^2 = 1) for a modified hyperbolic plane rotation, such that, y1 := 1/c * x1 - s/c * x2 = sqrt(x1^2 - x2^2), y2 := -s * y1 + c * x2 = 0, given two real numbers x1 and x2, satisfying either x1 = x2 = 0, or abs(x2) < abs(x1).Specification
SUBROUTINE MA02FD( X1, X2, C, S, INFO ) C .. Scalar Arguments .. DOUBLE PRECISION X1, X2, C, S INTEGER INFOArguments
Input/Output Parameters
X1 (input/output) DOUBLE PRECISION On entry, the real number x1. On exit, the real number y1. X2 (input) DOUBLE PRECISION The real number x2. The values x1 and x2 should satisfy either x1 = x2 = 0, or abs(x2) < abs(x1). C (output) DOUBLE PRECISION The cosines c of the modified hyperbolic plane rotation. S (output) DOUBLE PRECISION The sines s of the modified hyperbolic plane rotation.Error Indicator
INFO INTEGER = 0: succesful exit; = 1: if abs(x2) >= abs(x1) and either x1 <> 0 or x2 <> 0.Further Comments
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