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Taylor expansion agrees <strong>with</strong> that of exp(−δ/ǫ) through terms of degree 4, <strong>and</strong><br />

its value always lies in the interval (0, 1). Thus the solutions of the boundary<br />

value equation converge geometrically toward the <strong>slow</strong> manifold along its sta-<br />

ble manifold <strong>with</strong> increasing <strong>time</strong>. If the mesh intervals have lengthδ≤ǫ, then<br />

the relative error of the decrease satisfies<br />

0< ρ j( δ<br />

ǫ )−exp(δ<br />

ǫ )<br />

exp( δ<br />

ǫ )<br />

< 0.0015<br />

For large values ofδ/ǫ, the solution is no longer accurate near t=a if the bound-<br />

ary conditions do not satisfy y0 = (x1)0+ǫ. A similar, but simpler argument<br />

establishes that the solution of the discretized problem converges to the <strong>slow</strong><br />

manifold at an exp<strong>one</strong>ntial rate <strong>with</strong> decreasing <strong>time</strong> from t = b. Thus, the<br />

boundary value solver is stable <strong>and</strong> yields solutions that qualitatively resem-<br />

ble the exact solution for all meshes when applied to this linear problem. In<br />

particular, the solution of the discretized problem is exp<strong>one</strong>ntially close to the<br />

<strong>slow</strong> manifold away from the ends of the <strong>time</strong> interval [a, b]. As the mesh size<br />

decreases to zero, the algorithm has fourth-order convergence to the exact solu-<br />

tion.<br />

4.4 Numerical Examples<br />

4.4.1 Bursting Neurons<br />

This section on the Terman modification of the Morris-Lecar model appeared in<br />

the original paper [55] but has been omitted here for brevity.<br />

105

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