## A note on the oscillation of solutions of the differential equation $$y''+\lambda q(t)y=0$$ with an almost periodic coefficient.(English)Zbl 0615.34043

Let $$q\neq 0$$ be a (real) almost periodic function. The following theorem is proved: The equation $$y''+\lambda q(t)y=0$$ is oscillatory for every $$\lambda$$, $$\lambda\in R-\{0\}$$ if and only if $$M\{q\}=0$$ (M$$\{$$ $$q\}$$ is the mean value of the function q).

### MSC:

 34C99 Qualitative theory for ordinary differential equations 34A30 Linear ordinary differential equations and systems
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### References:

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