interpolation: accuracy of deg-20 interpolating polynomial

calchere

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An interpolating polynomial of degree 20 is to be used to approximate e^(-x) on the interval [0, 2]. How accurate will it be.

\(\displaystyle [f(x) - p(x)| \le \frac{1}{{4(n + 1)}}M(\frac{{b - a}}{n})^{n + 1}\)

|I don't know how to find M in this equation, but i'm not even sure I can use this equation.
The answer is 4.3*10^(-14)

Any help would be appreciated.
Thanks
 
calchere said:
An interpolating polynomial of degree 20 is to be used to approximate e^(-x) on the interval [0, 2]. How accurate will it be.

\(\displaystyle [f(x) - p(x)| \le \frac{1}{{4(n + 1)}}M(\frac{{b - a}}{n})^{n + 1}\)

|I don't know how to find M in this equation, but i'm not even sure I can use this equation.
The answer is 4.3*10^(-14)

Any help would be appreciated.
Thanks
Use Taylor's expansion and the error will be bounded by the maximum value of the residual term.
 
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