Thanks for your reply,
I saw many reviews of different function generators. But none of them had a stable output when connected to an oscilloscope. For example, in a review of the Uni-T model UTG962e, when set to 5Hz, the output displayed by the oscilloscope was between 4.95Hz and 5.03Hz. In none of the models that I saw, they did not have a completely accurate output even at low frequencies.
Do all the low-priced models have approximate output and only the expensive models like Keysight have fully accurate output?
I need a model that can have accurate and stable output up to two to three decimal places. For example, when I set the output to 4500.25 Hz, the exact output is this frequency.