On take , and someone proposes three boundary conditions: y(0)=0, y(1)=0, y'(0)=0.…

PHYSICS · Subjective · Fermi University Physics · Mathematical Methods for Physics · Ordinary differential equations · Function spaces and operator theory

Conditions of Validity, Ch Sturm-Liouville theory: the spectral theorem for a differential operator

Problem

On [0,1][0,1] take Ly=−y′′\mathcal{L}y=-y'', and someone proposes three boundary conditions: y(0)=0,y(1)=0,y′(0)=0.y(0)=0, \qquad y(1)=0, \qquad y'(0)=0. They compute the boundary form B(f,g)=[fg′−f′g]01B(f,g)=[fg'-f'g]_0^1 for two functions f,gf,g satisfying all three conditions, find it vanishes, and conclude that (L,D)(\mathcal{L},\mathcal{D}) is a good self-adjoint Sturm-Liouville problem. Decide whether this conclusion is correct, and if not, say what has gone wrong.

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