** Matrix logarithm. **

** L = LOGM(A) is the matrix logarithm of A. **

** Complex results are produced if A has negative eigenvalues. **

** A warning message is printed if the computed expm(L) is not close to A. **

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** [L,esterr] = logm(A) does not print any warning message, but **

** returns an estimate of the relative residual, norm(expm(L)-A)/norm(A). **

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** If A is real symmetric or complex Hermitian, then so is LOGM(A). **

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** Some matrices, like A = [0 1; 0 0], do not have any logarithms, **

** real or complex, and LOGM cannot be expected to produce one. **

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** See also EXPM , SQRTM , FUNM . **

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