Faculty use

Local Truncation, Global Error and Convergence

Reward correct mathematics, explicit units, conditions, and hypotheses, interpretation, and verification. Equivalent valid reasoning should receive credit.

Problem 1

It should be approximately halved.

Problem 2

Solve with h,h/2,h/4 and compare differences or against a reference solution to estimate error order.

Problem 3

Definitions should identify the equation type, dependent and independent variables, parameters, conditions, units or domain, and the hypotheses behind separating one-step defect from accumulated solution error. Use the formulas local defect for Euler O(h²); global Euler error O(h).

Problem 4

A strong error analysis identifies the first step that violates classification, algebra, theorem hypotheses, units, initial/boundary data, or numerical assumptions; then repairs that step and re-verifies the final result.

Problem 5

Application responses vary. Require defined variables, a compatible differential-equation model connected to simulation, control, orbital motion, chemical kinetics, heat transfer, and computational engineering, a complete computation, interpretation, and limitations.

Problem 6

Accept two independent checks appropriate to the task: differentiation/substitution, initial or boundary conditions, dimensional analysis, phase-line or stability evidence, residuals, step refinement, conservation/energy checks, data comparison, or a second method.

Scoring guidance

Six problems × 10 points: 5 mathematical accuracy, 2 structure/justification, 2 verification/interpretation, 1 notation and communication.

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