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1d
comment Computing an inexact derivative with some terms preserved in exact form
Use something like Rationalize[f[x], 10^-6] to force all the subexpressions in f[x] to be converted to exact quantities (within width-10^-6 bins).
May
26
comment Continuous background color of adjacent cells
I have promoted my comment(s) to an answer.
May
26
answered Continuous background color of adjacent cells
May
25
comment Continuous background color of adjacent cells
I achieved this result by typing Hello and World in 2 successive text cells, then I selected the cell brackets, opened the option inspector, then I altered the values displayed at Cell Options / Display Options / CellMargins.
May
25
comment Continuous background color of adjacent cells
Cell["Hello", "Text", CellMargins->{{66, 10}, {0, 0}}, Background->RGBColor[0.87, 0.94, 1]] followed by Cell["World", "Text", CellMargins->{{66, 10}, {0, 0}}, Background->RGBColor[0.87, 0.94, 1]].
May
25
comment Continuous background color of adjacent cells
You can use the CellMargins option of Cell to do what you want.
May
19
comment How to plot an implicit function; how to plot contours of a surface
I see you have now fixed the typo. I should really check that my code works AFTER I have finished doing all of my editing ...
May
19
answered How to summarize the coefficient in Notation?
May
19
answered How to plot an implicit function; how to plot contours of a surface
Apr
30
comment How do I find the area between two polar curves?
I have 10.1 on OS X and your Area[region] gives the message Area::nmet: Unable to compute the area of region ImplicitRegion[...].
Apr
30
comment How to label only leaves in TreeForm?
A quick-and-dirty solution is encoding /. List -> "" // TreeForm.
Apr
30
comment Deciphering output messages using Solve
{Transpose[A].L1.A == L1, Transpose[A].L5.A == L5} // Reduce immediately gives you something useful.
Apr
22
comment Reduce gives wrong solutions
I wonder how this ties in with the documentation, which says "The result of Reduce[expr,vars] always describes exactly the same mathematical set as expr. ".
Apr
19
comment Efficient way to sum all the primes below $N$ million in Mathematica
FWIW, Total[Prime /@ Range[PrimePi[10^9]]] evaluates to 24739512092254535 — i.e. the same as your trial 2 result. The computation took a few minutes, and the peak kernel memory usage was about 4.7GB.
Apr
9
comment many indefinite integrals do not evaluate in 10.1, looking for the cause
I have seen cases with definite coefficients for which Mathematica gives the right or wrong answer depending on where the integration limits are located. As far as I could tell, the errors occurred when Mathematica was being inconsistent with how it handled different branches of the integrand.
Apr
9
comment many indefinite integrals do not evaluate in 10.1, looking for the cause
I suspect that this "regression" has to do with the presence of (complicated) branch points and branch cuts in the integrand, whose location depends on the value(s) of the parameter(s) in the integrand, and which have to be handled with extreme care if you want to get the correct result. Previously, Mathematica gave results that could be incorrect in such cases, so I presume Mathematica has been "regressed" whilst they work out a framework for handling such cases correctly.
Apr
6
comment Forcing solutions to avoid Root[]
The documentation says that ToRadicals[expr] attempts to express all Root objects in expr in terms of radicals.
Mar
30
revised General function for the expansion of a polynomial of operators
deleted 3 characters in body
Mar
30
revised General function for the expansion of a polynomial of operators
added 1 character in body
Mar
30
answered General function for the expansion of a polynomial of operators