Mathematica

Defining UpValues
Dear Group, consider the following code: func[sys_Integer] := sys; func /: func[sys_Integer][args___] := sys + 1; func[sys_Function] := sys; { func[1], func[1][2], func[# + 2 &], func[# + 2 &][2] } Is there a way to define func such a way that when the main argument is an Integer, any further a... 7 Jul 2010 07:57

FindRoot with parameterized interpolated function
solnn[a_?NumericQ] := NDSolve[{ x'[tt] == a*y[tt], y'[tt] == -x[tt], x[0] == 1, y[0] == 0}, {x, y}, {tt, 0, Pi}][[1]] FindRoot[ (x /. solnn[1])[t] - (y /. solnn[1])[t] == 0, {t, 2}] {t->2.35619} f[a_?NumericQ, t_?NumericQ] := (x /. solnn[a])[t] - (y /. solnn[a])[t] Plot3D[f... 5 Jul 2010 06:42

a 4d algebraic geometry problem
Q(x,y,z,t)=x2+y2+z2+t2+x*t+y*t+z*t is the lattice form of Korkine and Zolatarreff from Advanced Number Theory, Harvey Cohn, Dover Books,1963, Page 89 It has basis vectors: v1={1,0,0,0} v2={0,1,0,0} v3={0,0,1,0} v4={-1,-1,-1,2} If f(x)=3*x2+3*x*t+t2 there is a three fold symmetry 3*Q(x,y,z,t)=f(x)+f(y)+... 5 Jul 2010 22:09

SyntaxInformation Question
Hi, In the ref/SyntaxInformation in the Help there is the following example or explanation can be found: "f can have any number of arguments, but each should be a two-element list:" SyntaxInformation[f] = {"ArgumentsPattern" -> {{_, _} ...}}; {f[{x, y}, {a, b}], f[x, {a, b}, {x, y, z}]}; ... 7 Jul 2010 07:56

The side-effects of mixing TraditionalForm inside expressions.
FYI, When I typed the following: ----------------------------- Clear[z] c = 1 + I; p = -9 + 3*I; t = 3.3; d = 1 - Exp[t*p]/z; expr1 = c/TraditionalForm@d; expr2 = c/d; (expr1 - expr2) /. z -> 1 -------------------------------- I was expecting to get ZERO, as I do when I do not use TraditionalForm,... 8 Jul 2010 03:42

JLink NaN Support
The support for NaN -> Indeterminate over JLink from Java -> Mathematica is completely broken. double[] f1() { return new double[]{Double.NaN}; } double[] f2() { return new double[]{1/0D}; } Evaluating f1 from Mathematica will return {-1024.} Evaluating f2 from Mathematica will kill the kernel. The desired ... 4 Jul 2010 06:51

Wolfram Alpha app for iPhone is now €0.79
Wolfram Alpha app for iPhone is now =800.79. Thought you might want to know. Cheers -- Sjoerd ... 5 Jul 2010 06:42

FindRoot with parameterized interpolated function from NDSolve
I have an interpolated function obtained as the solution to a system of ODEs via NDSOlve. The system and the solution depend on a number of parameters. I then want to plug this function into FindRoot to find the numerical solution of a system of equations which depend on both the dependent variable of the ODEs an... 6 Jul 2010 05:42

Is it possible to query current plot range values (or have
Some of my plots contain vertical lines for alignment. To make sure the lines extend from the top to the bottom of the plot frame, I typically give those lines large values for +y and -y coordinates. This has an unfortunate side effect that the directive PlotRange->All now considers my line to be a part of the plo... 5 Jul 2010 06:42

Display/manipulating numeric values inside a DynamicModule[]
Recently, I've been using DynamicModules[] to interactively explore some plots that I make -- by introducing a locator, whose coordinates allow me to trace the plotted data in some fashion (e.g. by displaying the function value for the x coordinate of the locator, or finding the closest plotted point to a locator i... 5 Jul 2010 06:42