拉格朗日乘数法示例4
几何画板及绘图内容加载中,请稍等……
①本范例演示了在二维平面上使用拉格朗日乘数法寻找函数在约束条件下的极值点;②涉及核心数学概念包括向量、导数、函数优化、线性方程组;③作图要点提炼自构造摘要,使用了Simplify, Point, Vector, Angle, LaTeX, Textfield, CurveCartesian, Segment, Text, RemoveUndefined, Element, Sequence等GeoGebra命令/对象;④适合大学微积分、数学分析等课程的教学演示,帮助学生直观理解抽象的优化问题。
GeoGebra 命令及参数
Simplify(Derivative[f, y, 1]) → fy'Simplify(Derivative[f, x, 1]) → fx'LeftSide(Cu_g) → gSimplify(Derivative[g, y, 1]) → gy'Simplify(Derivative[g, x, 1]) → gx'Point(Cu_g) → BVector(B, B + UnitVector[Vector[B, Dg]] / 3) → u_gVector(B, B + UnitVector[Vector[B, Df]] / 3) → u_fAngle(u_g, u_f) → αLaTeX(f, true) → text8aLaTeX(Cu_g, true) → text8bTextfield(f) → InputBox3Textfield(Cu_g) → InputBox4Zip((x(a), y(a), f(a)), a, Sequence[Point[Cu_g, t / n], t, 0, n]) → lg_1Textfield(n) → InputBox5CurveCartesian(sqrt(t), sqrt((1 - t^(3)) / 3), f(sqrt(t), sqrt((1 - t^(3)) / 3)), t, 0, 1) → q1CurveCartesian((-sqrt(t)), sqrt((1 - t^(3)) / 3), f((-sqrt(t)), sqrt((1 - t^(3)) / 3)), t, 0, 1) → q2Surface((1 - (3 * t^(2)))^(1 / 6), t, u, t, -1 / sqrt(3), 1 / sqrt(3), u, -1.2, 1.2) → g1Surface((-(1 - (3 * t^(2)))^(1 / 6)), t, u, t, -1 / sqrt(3), 1 / sqrt(3), u, -1.2, 1.2) → g2CurveCartesian((-sqrt(t)), (-sqrt((1 - t^(3)) / 3)), f((-sqrt(t)), (-sqrt((1 - t^(3)) / 3))), t, 0, 1) → q1aCurveCartesian(sqrt(t), (-sqrt((1 - t^(3)) / 3)), f(sqrt(t), (-sqrt((1 - t^(3)) / 3))), t, 0, 1) → q2aRotateText(text3, 90°) → text5TableText(Append["N", 1…Length[l2]], Append["\fgcolor{red}{Cp}", l2], Append["\fgcolor{blue}{f}(\fgcolor{red}{C_p })", l2fa], Append["(\dot{f_x},\dot{f_y})", l2xy'_fa], Append["(\dot{g_x},\dot{g_y})", l2xy'_ga], Append["λ_x", lλ2ax], Append["λ_y", lλ2ay], Append["\widehat{\dot{g}\dot{f}} ", lα2], "c|_") → tTab2Zip(Text["(" + (SurdText[x(a)]) + "," + (SurdText[y(a)]) + ")", (0, 0), true, true], a, l2) → l2surdZip(Text["(" + (SurdText[x(a), {sqrt(2), sqrt(3), sqrt(5), sqrt(10), cbrt(2), cbrt(3), cbrt(5)}]) + "," + (SurdText[y(a), {sqrt(2), sqrt(3), sqrt(5), sqrt(10), cbrt(2), cbrt(3), cbrt(5)}]) + ")", (0, 0), true, true], a, l1) → l1surdTableText(Append["N", 1…Length[l1]], Append["\fgcolor{red}{Cp}", l1], Append["\fgcolor{blue}{f}(\fgcolor{red}{C_p })", l1fa], Append["(\dot{f_x},\dot{f_y})", l1xy'_fa], Append["(\dot{g_x},\dot{g_y})", l1xy'_ga], Append["λ_x", lλ1ax], Append["λ_y", lλ1ay], Append["\widehat{\dot{g}\dot{f}} ", lα1], "c|_") → tTab1Segment(B, C) → f_1Text("∇g", Point[u_g, 1]) → text25gText("∇f", Point[u_f, 1]) → text25fSimplify(fx'(x, y) - (gx'(x, y) * fy'(x, y) / gy'(x, y))) → Cu_xfSimplify(fy'(x, y) - (gy'(x, y) * fx'(x, y) / gx'(x, y))) → Cu_yfRemoveUndefined(Zip[Vector[c, c + UnitVector[a] / 3], a, l1xy'_f, c, l1]) → lvec1_fRemoveUndefined(Zip[Vector[c, c + UnitVector[a] / 3], a, l2xy'_f, c, l2]) → lvec2_fRemoveUndefined(Zip[Vector[c, c + UnitVector[a] / 3], a, l1xy'_g, c, l1]) → lvec1_gRemoveUndefined(Zip[Vector[c, c + UnitVector[a] / 3], a, l2xy'_g, c, l2]) → lvec2_gTextfield(txtCu01_x) → InputBox1Textfield(txtCu01_x) → InputBox2Element(l1, Indexmax1) → Amax1_1Element(l1, Indexmin1) → Amin1_1Element(l2, Indexmin2) → Amin2_1Zip(Segment[a, b], a, l1, b, l1f) → l1segSequence(Text[i, l1(i) - (0.2, 0.1)], i, 1, lä1) → l1txtSequence(Text[i, l2(i) - (0.2, 0.1)], i, 1, lä2) → l2txtZip(Segment[a, b], a, l2, b, l2f) → l2segElement(l1f, Indexmax1) → Amax13d_1Element(l2f, Indexmax2) → Amax23d_1Element(l1f, Indexmin1) → Amin13d_1Element(l2f, Indexmin2) → Amin23d_1Element(l1f, 5) → Amin13d_2Element(l1, 6) → Amax1_2Element(l2, 6) → Amax2_2Element(l2, Indexmax2) → Amax2_1Element(l1f, 6) → Amax13d_2Element(l2f, 6) → Amax23d_2Element(l2f, 5) → Amin23d_2Element(l1, 5) → Amin1_2Element(l2, 5) → Amin2_2
AI 绘图提示语参考
绘制一个二维函数的优化问题,展示使用拉格朗日乘数法找到极值的过程。包含函数曲线、约束曲线及其切线向量,标示梯度向量和单位向量,并绘制出梯度向量之间的角度。用不同颜色区分函数和约束曲线,并标注关键点和向量,最后用表格列出各点的坐标、函数值、梯度向量及拉格朗日乘数。
以上提示语为根据原始绘图命令整理而来,仅供参考。