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+--- Thread: Implicit differentiation on HP Prime. (/thread-133.html)
Implicit differentiation on HP Prime. - John P - 12-17-2013 03:37 AM
Hi Everybody,
Does anybody knows how to implicitly differentiate functions on HP Prime?
Thanks.
RE: Implicit differentiation on HP Prime. - Han - 12-17-2013 04:38 AM
When I do:
diff(3*7^x-x*g(x^2),x)
I get:
-x*diff(g(x^2),x)+3*7^x*LN(7)-g(x^2)
which is pretty much correct except it did not simplify diff(g(x^2),x) since it has no idea what g(x) is -- I intentionally left g(x) undefined for this example.
RE: Implicit differentiation on HP Prime. - John P - 12-17-2013 05:34 AM
Thanks. I tried something similar but I could not solve for diff(y(x),x). I think results with diff(y(x),x) are pretty useless because you can't use them in farther calculations. I hope they will implement implicit differentiation i next ROM update.
RE: Implicit differentiation on HP Prime. - Han - 12-17-2013 05:55 AM
(12-17-2013 05:34 AM)John P Wrote: Thanks. I tried something similar but I could not solve for diff(y(x),x). I think results with diff(y(x),x) are pretty useless because you can't use them in farther calculations. I hope they will implement implicit differentiation i next ROM update.
Use subst() or convert the result into a string with STRING(). Then use REPLACE() and (to replace "diff(y(x),x)" with just "Yy" for example) and then convert back to a symbolic via EXPR() and continue with solving. Just make sure to add single quotes around the string before using EXPR(). You can probably automate this in a program.
RE: Implicit differentiation on HP Prime. - John P - 12-17-2013 07:47 AM
I can do it manually, it works fine with replace, but I can't make program to do the staff. Always getting an error when exiting program mode.