xi=[ 0.1 0.2 0.3 0.4 0.5 0.6]

yi=[1.621 1.408 1.266 1.170 1.104 1.060]

What is d ln(yi) / d ln(xi) = ?

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- October 23rd 2010, 05:01 PMchronicalsNumerical differentiation problem?
xi=[ 0.1 0.2 0.3 0.4 0.5 0.6]

yi=[1.621 1.408 1.266 1.170 1.104 1.060]

What is d ln(yi) / d ln(xi) = ? - October 23rd 2010, 06:35 PMJhevon
- October 23rd 2010, 10:01 PMchronicals
I write this in matlab:

>> x=0.1:0.1:0.6

x =

0.1000 0.2000 0.3000 0.4000 0.5000 0.6000

y=[1.621 1.408 1.266 1.170 1.104 1.060];

>> k=log(y)

k =

0.4830 0.3422 0.2359 0.1570 0.0989 0.0583

>> l=log(x)

l =

-2.3026 -1.6094 -1.2040 -0.9163 -0.6931 -0.5108

and this our result:

>> z=diff(k)./diff(l)

z =

-0.2032 -0.2622 -0.2741 -0.2602 -0.2231

but in my book the result is different:

d ln(y) / d ln (x)= [ -0.246 - -0.249 - -0.2.44 -]

i must reach the book's result, but how?