reallog
7-21
7reallog
Purpose Natural logarithm for nonnegative real inputs.
Syntax Y = reallog(X)
Description reallog is an elementary function that operates element-wise on matrices.
reallog returns the natural logarithm of X. The domain of reallog is the set
of all nonnegative real numbers. If
X is negative or complex,reallog issues an
error message.
reallog is similar to the MATLAB log function;however, the domainof log is
much broader than the domain of
reallog. The domain of log includes all real
and all complex numbers. If
Y is real, you should use reallog rather than log
for two reasons.
First,subsequent accessof
Y may execute moreefficientlyif Y iscalculatedwith
reallog rather than with log.Usingreallog forces the MATLAB Compiler to
impute a real type to
X andY.Usinglog typicallyforcestheMATLAB Compiler
to impute a complex type to
Y.
Second, the compiled version of
reallog may run somewhat faster than the
compiledversionof
log. (However,the interpretedversio n of reallog may r un
somewhat slower than the interpreted version of
log.)
See Also exp, log, log2, logm, log10, realpow, realsqrt
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