Re: [Gnuplot-info] log(xy) not turning out to be log(x) + log(y)

[Hans-Bernhard B. <HBB...@t-...>]

On 24.11.2011 08:11, Anirban Gangopadhyay wrote:
>   p(x,y,n1,n2) = log10((x**n1) * (abs(y)**n2)) + log10(x)
>   q(x,y,n1,n2) = log10((x**n1) * x * (abs(y)**n2))

>   plot 'tsorted499diffVsB.dat' u (p(499,$1,3,0.66)):(p(499,$5,2,1)) every
> ::27::44 w p ls 1 t 'N=499(add)', 'tsorted499diffVsB.dat' u
> (q(499,$1,3,0.66)):(q(499,$5,2,1)) every ::27::44 w p ls 2 t
> 'N=499(multiply)'

Was there really no simpler way you could demonstrate the problem?

> Note that the functions p and q are the same function using the idea that
> log(product of two numbers) = sum of log of the two numbers, but the plot
> command does not result in overlapping plots.


I have attached the data
> file  'tsorted499diffVsB.dat' and the output file 'plot499.ps' here.

Sorry, but attachments sent via mailing lists often don't work very 
well.  Yours didn't make it.

Any
> help/clue as to what might be happening here will be appreciated.