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1 | | -Use case scenarios of the approximation technique we discuss have their own constraints and limitations. |
| 1 | +The approximation technique above has its own constraints and limitations. |
2 | 2 | For instance, approximation requirements should have precisely specified exponent $j$ in $X^j$ because |
3 | 3 | for each $j$ there is a matching polynomial $P(m,X,N)$. |
4 | 4 | Perfectly, there should be a set precompiled polynomials $P(m,X,N)$ matching precise exponent $j$ in $X^j$ over |
5 | | -precisely defined approximation range with required error of approximation $E$ as a constraint. |
| 5 | +exactly defined approximation range with required error of approximation $E$ as a constraint. |
6 | 6 | Generally, the approximation of power function $X^j$ by $P(m,X,N)$ can be broken down into the following steps |
7 | 7 | \begin{enumerate} |
8 | 8 | \item Define the exponent $j$ in $X^j$ |
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31 | 31 | \end{align*} |
32 | 32 | Therefore, for each two consequential points $N=X, N=X+1$ the absolute difference is 1, making that range |
33 | 33 | at least $1\%$ percentage error for $X^j \leq 100$. |
34 | | -I have chosen the approximation range $10 \leq X \leq 15$ and $j=3$ intentionally to show the spline approximation with |
| 34 | +The approximation range $10 \leq X \leq 15$ and exponent $j=3$ are chosen intentionally to show the spline approximation with |
35 | 35 | percentage error threshold less than $1\%$. |
36 | 36 | Therefore, to approximate $X^3$ in the range $10 \leq X \leq 15$, we use the following spline function |
37 | 37 | \begin{align} |
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51 | 51 | \includegraphics[width=1\textwidth]{sections/images/08_plots_of_cubes_power_with_p_2_10_15} |
52 | 52 | ~\caption{ |
53 | 53 | Approximation of cubes $X^3$ by splines~\eqref{eq:spline_approximation_of_cubes}. |
54 | | - Convergence interval is $10 \leq X \leq 15$ with percentage error $E\leq 1\%$. |
| 54 | + Convergence interval is $10 \leq X \leq 15$ with percentage error $E < 1\%$. |
55 | 55 | } |
56 | 56 | \label{fig:08_plots_of_cubes_power_with_p_2_10_15} |
57 | 57 | \end{figure} |
58 | 58 | where the spline knots are integers in the range $10 \leq N \leq 14$. |
59 | 59 |
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60 | 60 | The same principle applies for even exponent $j=4$ in $X^j$ with the same convergence interval $10 \leq X \leq 15$ |
61 | | -and approximation error under $1\%$ constraints |
| 61 | +and approximation error under $1\%$ |
62 | 62 | \begin{align} |
63 | 63 | X^4 \approx |
64 | 64 | \begin{cases} |
65 | 65 | P(1,X,10) \cdot X = -2300X + 330X^2, & 10 \leq X < 11 \\ |
66 | | - P(1,X,10) \cdot X = -3025X + 396X^2, & 11 \leq X < 12 \\ |
67 | | - P(1,X,10) \cdot X = -3888X + 468X^2, & 12 \leq X < 13 \\ |
68 | | - P(1,X,10) \cdot X = -4901X + 546X^2, & 13 \leq X < 14 \\ |
69 | | - P(1,X,10) \cdot X = -6076X + 630X^2, & 14 \leq X \leq 15 |
| 66 | + P(1,X,11) \cdot X = -3025X + 396X^2, & 11 \leq X < 12 \\ |
| 67 | + P(1,X,12) \cdot X = -3888X + 468X^2, & 12 \leq X < 13 \\ |
| 68 | + P(1,X,13) \cdot X = -4901X + 546X^2, & 13 \leq X < 14 \\ |
| 69 | + P(1,X,14) \cdot X = -6076X + 630X^2, & 14 \leq X \leq 15 |
70 | 70 | \end{cases} |
71 | 71 | \label{eq:spline_approximation_fourth_power} |
72 | 72 | \end{align} |
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76 | 76 | \includegraphics[width=1\textwidth]{sections/images/09_plots_of_fourth_power_with_p_2_10_15_times_x} |
77 | 77 | ~\caption{ |
78 | 78 | Approximation of $X^4$ by splines~\eqref{eq:spline_approximation_fourth_power}. |
79 | | - Convergence interval is $10 \leq X \leq 15$ with percentage error $E\leq 1\%$. |
| 79 | + Convergence interval is $10 \leq X \leq 15$ with percentage error $E < 1\%$. |
80 | 80 | } |
81 | 81 | \label{fig:09_plots_of_fourth_power_with_p_2_10_15_times_x} |
82 | 82 | \end{figure} |
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