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Doug Huffman

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Calculators and computers were prohibited in my schooling and early in my professional career. I can still use a slide rule.

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Try differentiating ##f(x) = x^x##

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Don't know what you mean. Haven't covered that yet.Try differentiating ##f(x) = x^x##

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When you do cover it, you might find the humble logarithm quite useful!

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Mark44

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Yeah, me, too. I still own about five of them.

Calculators and computers were prohibited in my schooling and early in my professional career. I can still use a slide rule.

Try differentiating ##f(x) = x^x##

Well, then you have probably covered exponential functions such as y = eDon't know what you mean. Haven't covered that yet.

##y = 10^x## is equivalent to x = log

By "equivalent to" I mean that the graphs of y = 10

The concept of logs is also used for plotting data when either the "x" or "y" values (or both) cover a range of values of several orders of magnitude. Such plots are done on semi-log paper or log-log paper.

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You can also view it's inverse, the exponential e, as a way to turn additive things into multiplicative things.

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Nugatory

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Entropy, for example. It is really convenient to be able to add entropies.You can just view the logarithm as a way to turn multiplicative things into additive things

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It's necessary for doing stuff such as solving ##3 = 10^x## for x, solving certain equations, expressing something in function of something else etc. which is not what I would classify as "useless", but you are just being introduced to the concept and playing around with what it means, in which case it's normal that you don't see its use yet.

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Originally, I think logarithms were invented to help do calculations.

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Doug Huffman

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Practical fission power levels vary over thirteen decades, in my plant's application, from source range Counts Per Second - CPS, through intermediate range detector current amperes, and into one and a half decades of power range indication 1% to 150%.

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Chestermiller

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Chet

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Or, "Same reason we have subtraction and division when we already have addition and multiplication."?Once you decide that exponents are needed and inverse functions are needed, you pretty much already have logarithms. Calling them log is just giving a name to something that is already there, namely, the inverse of an exponential function.

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