On real logarithms of nearby matrices and structured matrix interpolation

Theoretical and algorithmic results are given for the numerical computation of real logarithms of nearby matrices. as an application, and an original motivation for this study, interpolation for sequences of invertible matric es is considered particularly for matrices with a given structure (for exam ple, orthogonal, symplectic, or positive definite), so that the resulting i nterpolants share the structural properties of the data. Error analysis, im plementation details and examples are provided. (C) 1999 Elsevier Science B .V. and IMACS. All rights reserved.