Quantitative analysis of relaxation oscillator

In order to make quantitative predictions, we must locate the four corners of the oscillation A, B, C, and D. Two of these, A and C, correspond to the turning points in the g(a, 0) = 0 nullcline. For the present model these are also the turning points in the ass(p) locus, whose coordinates have been determined in eqns (4.66)-(4.68). We can content ourselves here with the leading-order forms with small y  

The a ordipates of points B and D will be the same as those of A and C respectively, as the jumps are represented by vertical lines in the phase plane. Thus we seek the other solutions to g(ot, 6) = 0 for these values of a. At point B, we must satisfy 

However, the temperature excess is large here, certainly 0B 6C y 2, so the exponent on the right-hand side reduces to e 1/r. Using this we then have for point B 

Here 0D 1, so we can neglect the departure of the exponential term from unity, giving 

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