RandomBits
Reputation
307
Next privilege 500 Rep.
Access review queues
 Sep 10 answered How to express and take symbolic derivative of expression with finite sum Sep 10 comment How to express and take symbolic derivative of expression with finite sum I also found the user of format in your answer (Format[a[k_]] = Subscript[a, k]) very useful. Sep 10 comment How to express and take symbolic derivative of expression with finite sum I was hoping to be able to get the result without explicitly adding all of the derivative and simplification rules. After following the link in your answer, I found that I could show Mathematica the relationship I intended between x[i] and x[j] with the following code: x /: D[x[i],x[j],NonConstants -> {x}] = KroneckerDelta[i,j]. Sep 6 comment How to express and take symbolic derivative of expression with finite sum @It'sPronouncedOiler Yes, 1<=i<=n. Is there some way I need to communicate that information to the D function? Sep 6 asked How to express and take symbolic derivative of expression with finite sum Aug 11 awarded Yearling Jul 9 awarded Curious Jun 26 awarded Teacher Mar 9 comment Convert logical relational expression to / from disjunctive and conjunctive forms? That works for my current test cases, but BooleanConvert seems to ignore the form specification for "DNF" and "CNF": BooleanConvert[!Reduce[!result]] produces the same result as BooleanConvert[!Reduce[!result], "DNF"] and BooleanConvert[!Reduce[!result], "CNF"]. Specifying "NAND" and "NOR" does produce the expected results. I'd like to try to understand why this produces the CNF form and add a few more test cases. Mar 9 asked Convert logical relational expression to / from disjunctive and conjunctive forms? Mar 6 comment How do I get a two-term polynomial with a leading negative sign to display in the correct (i.e. textbook) order? Is it the case that Plus@@MonomialList[expr] == expr for any expression? If so, then I can define a format: Format[xPlus[x___]] := Row[Riffle[{expr}, "+"]] and then xPlus := Plus and then use HoldForm[xPlus@@MonomialList[expr]] to the display ordering that I want while still having a valid expression when the hold is released (because the xPlus will be changed to Plus). Mar 5 revised How do I get a two-term polynomial with a leading negative sign to display in the correct (i.e. textbook) order? Added the results for using PolynomialForm Mar 5 comment How do I get a two-term polynomial with a leading negative sign to display in the correct (i.e. textbook) order? @Mr.Wizard: Yes, I already tried PolynomialForm and that produces the same results. I will add that information to the question because that will probably be a common thought pattern. Mar 5 asked How do I get a two-term polynomial with a leading negative sign to display in the correct (i.e. textbook) order? Mar 5 comment How does MakeBoxes handle an n-ary operator? This is working great. I have a similar function to replace power: xPower /: MakeBoxes[xPower[x_, y_ /; y < 0], form_] := SuperscriptBox[MakeBoxes[x, form], MakeBoxes[y, form]];. This keeps Mathematica from inverting negative integer exponents. Do I need to do anything to protect x and y in this case? And would it be something like this: HoldComplete[x] /. HoldComplete[elem_] :> MakeBoxes[elem, form]? Mar 5 comment How does MakeBoxes handle an n-ary operator? I understand the use of SetAttributes[xO, HoldAllComplete], but I am having trouble understanding the details of the rule inside of Replace. It looks like the gist of it is that you are safely evaluating MakeBox for each argument of xO. Mar 5 accepted How does MakeBoxes handle an n-ary operator? Mar 5 comment How does MakeBoxes handle an n-ary operator? Works perfectly, but it would have taken me an long and indeterminate amount of time to come to that solution. Thank you @Leonid. Mar 5 revised How does MakeBoxes handle an n-ary operator? Minor formatting fix Mar 4 asked How does MakeBoxes handle an n-ary operator?