I type
f1[x_] := 12 x^5 - 975 x^4 + 28000 x^3 - 345000 x^2 + 1800000 x
N[f1[15.5], 15]
and obtain 3.74112*10^6
BUT It´s not true!!! the result is larger than this solution, I think... BACAUSE...
RealDigits[f1[15.5]]
gives me, the result {{3, 7, 4, 1, 1, 2, 0, 6, 8, 7, 5, 0, 0, 0, 0, 0}, 7}
So,... I can´t understand that I tell Mathematica that I want to view 15 significative digits, and Mathematica DON´T show me 15 sgnificative digits!!!, only 6!!
How I can obtain more digits???? with N[...] or with //N ???
I can´t understand any differneces in precision with Mathematica
m1 = {15, 4, 8, 23, 10, 9, 5, 18, 30, 21}
m2 = {15`9, 4`9, 8`9, 23`9, 10`9, 9`9, 5`9, 18`9, 30`9, 21`9}
f1[x_] := 12 x^5 - 975 x^4 + 28000 x^3 - 345000 x^2 + 1800000 x
x0 = f1[m1]
x1 = N[f1[m1], 9]
x2 = N[f1[m2], 9]
In the last element of x_ you can see diferrences, and... I don´t know what is the best way to obtain an an result with a concrete number os significative digits.
In x2, I tell Mathematica that I want 9 significative digits but the result is different from the last element of x1 and x0
and
I don´t know what result is the correct!
What´s the best way to obtain the good result with a given precision??, in this concrete situation?
If you replace in the las line of code in x2 9 for 12 or 15, you obtain the same result!! I can´t understand the behaivour!!
N[f1[15 + 1/2], 15]
. See e.g., here (and references cited) for why: mathematica.stackexchange.com/questions/43714/… $\endgroup$ – ciao Mar 16 '14 at 22:07