** Matrix square root. **

** S = SQRTM(A) is the matrix square root of A. **

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

** A warning message is printed if the computed S*S is not close to A. **

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

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

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** If A is real, symmetric and positive definite, or complex, Hermitian **

** and positive definite, then so is the computed matrix square root. **

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

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

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** See also EXPM , LOGM , FUNM . **

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