wolfram mathematica - Unusual Solve[] behavior delay -
for project involved computing bond lengths spectroscopic data, used solve[] solve simple equation unknown. began noticing "unusual" behavior when changed input. specifically, when changed number , solve'd, result answer previously. executing code again, however, gives correct answer; it's there's delay of 1 execution. here's example: b = (11.09 + del)*2.998*10^10; c = h*1000*n*10^20/(8 \[pi]^2); h = 6.62618*10^-34; n = 6.02204*10^23; del = 0; solve[c/b == 0.97959253 r^2, r] executing gives {{r -> -1.24567}, {r -> 1.24567}} however, when change del = 0 del = 10 in above block, same answer when execute! when execute block second time, correct answer: {{r -> -0.903299}, {r -> 0.903299}} then, changing del = 10 del = 0 , executing gives: {{r -> -0.903299}, {r -> 0.903299}} and can imagine, executing block second time gives correct answer {{r -> -1.24567}, {r -> 1.24567}} there nothing special 0 , 10, 2 nu
