Search results
Results From The WOW.Com Content Network
In mathematics, the logarithm of a number is the exponent by which another fixed value, the base, must be raised to produce that number.For example, the logarithm of 1000 to base 10 is 3, because 1000 is 10 to the 3 rd power: 1000 = 10 3 = 10 × 10 × 10.
To more easily manipulate the expression, it can be rewritten as an exponential. b m = x {\displaystyle b^{m}=x} Applying log a {\displaystyle \log _{a}} to both sides of the equality, log a ( b m ) = log a ( x ) {\displaystyle \log _{a}(b^{m})=\log _{a}(x)}
The natural logarithm of a number is its logarithm to the base of the mathematical constant e, which is an irrational and transcendental number approximately equal to 2.718 281 828 459. [1]
The logarithmic decrement can be obtained e.g. as ln(x 1 /x 3).Logarithmic decrement, , is used to find the damping ratio of an underdamped system in the time domain.. The method of logarithmic decrement becomes less and less precise as the damping ratio increases past about 0.5; it does not apply at all for a damping ratio greater than 1.0 because the system is overdamped.
The first term li(x) is the usual logarithmic integral function; the expression li(x ρ) in the second term should be considered as Ei(ρ log x), where Ei is the analytic continuation of the exponential integral function from negative reals to the complex plane with branch cut along the positive reals. The final integral is equal to the series ...
Positive numbers less than 1 have negative logarithms. For example, = = + + = To avoid the need for separate tables to convert positive and negative logarithms back to their original numbers, one can express a negative logarithm as a negative integer characteristic plus a positive mantissa.
The exponential of a matrix A is defined by =!. Given a matrix B, another matrix A is said to be a matrix logarithm of B if e A = B.. Because the exponential function is not bijective for complex numbers (e.g. = =), numbers can have multiple complex logarithms, and as a consequence of this, some matrices may have more than one logarithm, as explained below.
The expression is left undefined since there is no complex number satisfying =. [ 1 ] When the notation log z {\displaystyle \log z} appears without any particular logarithm having been specified, it is generally best to assume that the principal value is intended.