log - This function computes the logarithm of a number.
log(argument)
This mathematical function allows the user to compute the natural logarithm of a number. The natural logarithm is the logarithm that has the constant e as its base. E is an irrationnal and transcendantal number. In litterature, you might find the log written as ln. The logarithm of a number x is the exponent y to which e must be raised to give x. Log x=y, where x=exp(y). The exponential is its inverse operation. This function is defined in the first quadrant and the 4th, meaning that 0<x<INF and -INF<y<INF.
Note: In the followings examples, the _ between the { should be removed to make it work.
One can use this function with integers: test(q(res={_{log(45);}}.),q(res=3.80666.)); With floats: test(q(res={_{log(4.5);}}.),q(res=1.50408.)); With another variable: test(q(res={_{ %include "/includes/extenso.sn"; a=3; log(a); }}.), q(res=1.09861.)); With a trigonometric function: test(q(res={_{ %include "/includes/extenso.sn"; a=cos(0); log(a); }}.), q(res=0.)); With the limits: test(q(res={_{ %include "/includes/extenso.sn"; log(0); }}.), q(res=INF.)); With an array: test(q(res={_{log(1,45,4.5);}}.),q(res=\[0,3.80666,1.50408\].)); But not with negative numbers: test(q(res={_{log(-1);}}.),q(res=NAN.)); Since this function is defined in the first and fourth quadrant, the x must always be positive. However, this returns an imaginary number, PI*i.
Written by Caroline Laplante, <claplante@sednove.com>
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1.0 2014-09-09 21:24:14 laplante@sednove.com