Ratio of functions -- automatically apply l'Hospital rule when needed

In summary, the speaker is asking if Mathematica has a feature to automatically switch to calculating the ratio f1'(x) / f2'(x) when necessary while avoiding errors and optimizing numerical precision. They also mention trying this manually and finding it to work automatically, but with errors when calculating a single value at a singularity.
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Swamp Thing
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I want to plot the ratio f1(x) / f2(x), where they have some common zeros. Does Mathematica have a feature that will do this, switching automatically to f1'(x) / f2'(x) when appropriate, avoiding F.P. errors and optimizing numerical precision?

If not, is there a good way to implement this?
 
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  • #2
After posting, I thought I'd just try it in the normal way and see what happens... it seems to be doing it automatically anyway, without specifying any feature.

Edit:
It avoids the 0/0 while plotting, but it gives an error when you calculate a single value at the singularity.
 
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1. Why is the use of l'Hospital's rule important in calculating the ratio of functions?

L'Hospital's rule is important because it provides a method for evaluating limits involving indeterminate forms, such as 0/0 or ∞/∞. These limits often arise when calculating the ratio of functions, and without l'Hospital's rule, it would be difficult or impossible to find the limit.

2. How do I know when to apply l'Hospital's rule when calculating the ratio of functions?

L'Hospital's rule should be applied when the limit of the ratio of two functions is in an indeterminate form, such as 0/0 or ∞/∞. This can be determined by evaluating the limit algebraically, or by graphing the two functions and observing their behavior near the point of interest.

3. Can l'Hospital's rule be applied to any limit involving the ratio of functions?

No, l'Hospital's rule can only be applied to limits involving indeterminate forms. If the limit of the ratio of functions is already in a determinate form, such as a finite number or infinity, then l'Hospital's rule is not applicable.

4. Are there any restrictions on the use of l'Hospital's rule when calculating the ratio of functions?

Yes, l'Hospital's rule can only be applied if both functions in the ratio are differentiable at the point of interest. Additionally, both functions must approach their limit at the same rate. If these conditions are not met, l'Hospital's rule cannot be used to evaluate the limit.

5. Is it always necessary to use l'Hospital's rule when calculating the ratio of functions?

No, l'Hospital's rule is not always necessary. In some cases, the limit of the ratio of functions can be evaluated using other methods, such as algebraic manipulation or substitution. However, l'Hospital's rule is a useful tool for evaluating limits that involve indeterminate forms, and can often simplify the calculation process.

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