Introduction
This page is meant to describe how to use the simple
calculator/derivation system written entirely in JavaScript. The basic
capabilities are symbolic derivation and expression evaluation.
Differentiation
Simply enter the equation to differentiate and change the variable to
differentiate with respect to if you want (by default it is x). Hit
derive and the answer will appear in the numeric evaluation
section. You can also change the number of times to differentiate to
get the second, third, etc. derivative.
Numeric evaluation
After differentiation, you may want to evaluate at specific
values. Just define the values for the variables and hit evaluate. The
definitions can contain references to other variables, and to indicate
a value for a derivative, use something like "y'=x"
Guessing numbers
After evaluation, you may get a result like .7071067811865476. Since
you are so smart, you immediately realize that this is sqrt(1/2). But
then you get 22.45915771836104. Bet you didn't know this is pi^e. Of
course, why you would get this as an answer is beyond me. However,
just in case you do get some numbers like these, and hit guess
numbers, the system will try to rewrite the numbers into a form that
may be more recognizable.
History
Every time you hit derive or evaluate, the equations or definitions
that you used for input are saved in the history. The most recently
used 25 items are saved. To re-use one of them, select one, and hit
the appropriate button to copy that expression to the corresponding
text field. The clear history button does what it says it does.
Input Expressions
Valid operators
() ^ * / + -
Valid functions
sqrt || sin || cos || tan || sec || csc || cot || ln || asin || acos || atan
Predefined values:
e || pi
Examples
Some examples of possible things that can be done.
- Differentiate x^x.
- Let f(x) = (sec(ln(x^sin(x))))^2*sqrt(x) + acos(x) / e^x. Find f'(x).
- Find value of above derivative at pi/4: f'(pi/4) = ?
- Let f(x) = y ln x. Find f'(3) when y = 4 and y' = 2
- Derive sqrt(sin(cos(tan(sec(csc(cot(ln(asin(acos(atan(e^(x*x/e+42)-pi))))))))))) for fun.
-
Suppose you want to know what n factorial is. Enter n for the number of times to
differentiate and differentiate the equation x^n. (see you can be creative with calculus...)
Other Links
Bugs
It doesn't match the name of the page. It started out as being a
pretty useless page. It is now kind of too useful to match the name of
the page. Oh well. If you do find any real bugs on the page, please do
tell me.
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