Related to https://github.com/kolosovpetro/AnEfficientMethodOfSplineApproximation

MathematicaPrograms.txt

(* Requires package: PlotsOfClosedForms.m, see https://github.com/kolosovpetro/AnEfficientMethodOfSplineApproximation*)

f1[X_] := X^7;
f2[X_] := P[3, X, 50];
absError[X_] := Abs[f1[X] - f2[X]];
relativeError[X_] := absError[X]/ Abs[f1[X]];
percentError[X_] := relativeError[X]*100;

(* Generate the table with step 0.1 *)
step = 0.1;
range = Range[20, 90, step];
table = Table[{x, f1[x], f2[x], absError[x], relativeError[x],
    percentError[x]}, {x, range}];

(* Print the table *)
Grid[Prepend[table, {"X", "X^7", "P", "ABS", "Relative" , "% Error"}],
  Frame -> All]


(* Generate plots *)
Plot[{X^5, 900 X^2 - 6000 X + 10624}, {X, 0, 6},
 PlotLabels -> "Expressions", AxesLabel -> {Automatic, F[X]},
 Epilog -> {Black, PointSize@Medium, Point[{4, 4^5}]},
 PlotStyle -> {Thickness[0.004]}]