Questions about how Mathematica evaluates expressions, tracing evaluation (Trace*), handling expressions in unevaluated form (Hold*, Unevaluated), nonstandard evaluation, etc.

learn more… | top users | synonyms

1
vote
1answer
118 views

About evaluation in Block

I'm completely puzzled by the following codes: Clear[func, f] a = x^2 + z; func[k_] := Block[{f}, (f[x_] := Evaluate[(a /. {z -> k})]; f[1])] func[2] ...
1
vote
1answer
366 views

How to tell Mathematica not to simplify an expression

While there is this question with a very similar title, it does not answer my question, which is: I have part of an input, in my case Re[Exp[I*x]] which ...
1
vote
1answer
160 views

Evaluate code to some point

How can I evaluate my code, up to some point? I don't want to evaluate all of my code always. I have to use Shift - Enter for every line from the first cell up to the point I want to be, and it's not ...
1
vote
1answer
231 views

Skip one step of the loop if there is an NIntegrate::eincr message

Is there a possibility of skipping one step of a loop if in this step there appears an error like NIntegrate::eincr? After skipping, the loop should go to the next ...
1
vote
1answer
241 views

Particular solutions of a Differential Equation not evaluated in a given case

Below first case which gives particular solutions of an OED correctly: ...
1
vote
1answer
37 views

Non-autonomous Dynamical system Sliding mode controller Error

This code is a simulation of a sliding mode controller of a non-autonomous dynamic. When I use ArcTan in input, I receive an error. ...
1
vote
0answers
61 views

How to Implement a “Function Object” suitable for NDSolve and Finite Element Method?

I have a bunch of methods that shoud return an expression that behave like a function, i.e. an expression that, when supplied with suitable arguments, evaluate to something. A simple ...
1
vote
0answers
38 views

Unexpected order of evaluation in ForAll

I noticed that ForAll behaves rather unexpectedly when its first argument is a symbol which has been Set in an outer scope. For ...
1
vote
0answers
82 views

How can I use L.Shifrin s code formatter package better

in the document of HoldAllComplete, it says: Evaluate cannot be used to override HoldAllComplete.. for example, when I'm ...
1
vote
2answers
59 views

Coordinates of MeshPoints

The output of a set of differential equations solved with NDSolve produces a series of curves and I need to obtain the spacing between these curves at a given level ...
1
vote
0answers
84 views

Smart pointer for Mathematica?

Would the implementation of the smart pointer idea be possible in Mathematica ? Let's say I have an object "o" of the form Class[object] where object is an Association, and Class has the HoldFirst ...
1
vote
0answers
107 views

How to make a graph of this function?

I need to plot the following function: ...
1
vote
1answer
51 views

Getting Gamma as a result for integration [closed]

When finding the mean from the distribution, fx = 4*x^3*Exp[-x^4] meanx = Integrate[x*fx, {x, 0, Infinity}] I get Gamma[5/4] Could someone explain what ...
1
vote
0answers
44 views

Question on Function in Replacement Operation

I am trying to create a replacement function which, depending on the input, gives an additional minus. In my example I have an undefined function a with two ...
1
vote
0answers
53 views

Is it possible to pipe the output of EvaluationMonitor to Excel?

I have an EvaluationMonitor setup to capture the points processed by NIntegrate. This is a case where the same function, integrated over the same region in cartesian coordinates yields a dramatically ...
1
vote
0answers
79 views

How to implement nested With as a single construct using functional programming (Fold)?

It is possible to define my own With construct where each local constant can depend on the previous defined local constants? I wish to replace something like this ...
1
vote
0answers
107 views

Expression for evaluating multiple functions?

I am constructing 3D data points for a plot and corresponding to specific conditions "manually". I define the values of five parameters [these I always have to define myself]. From those, I evaluate ...
1
vote
0answers
39 views

can I evaluate multiple cells at the same time? [duplicate]

my laptop has 2 cores, can I assign a core to evaluate one code, and the other core for another code in parallel instead of evaluating in sequence? thanks
1
vote
0answers
31 views

How to Plot a function that returns multiple values? [duplicate]

I have a function that returns multiple values, like this: f[x_] := ( (*... something ... *); {y1, y2}); They are computed together, so there's absolutely no ...
1
vote
0answers
389 views

Is there a way to stop evaluation immediately?

Sometimes I'll have a loop that I accidentally made too big. I'll evaluate, and MM will try to run through the entire loop. The program itself doesn't actually seem frozen... I can go to Evaluation-> ...
1
vote
1answer
126 views

Printing intermediate calculations in an external file, while suppressing the output in the notebook

I'm trying to construct a text-file that contains all the operations that Mathematica performs when evaluating an expression. However, i'd like to suppress all output in the notebook in which I'm ...
1
vote
0answers
46 views

Define a Plot3D function with custom options [duplicate]

I am trying to define a Plot3D function with custom options, following (this previous SE question), but I'm running into a brick wall. I've narrowed the problem to the following 'toy' code: ...
1
vote
0answers
55 views

Confusing efficiency and evaluation when returning pure functions? [duplicate]

I have a function that takes some time to evaluate, that's meant to be a polynomial approximation to a function. The polynomial is defined by a list of coefficients, so I have the function ...
1
vote
0answers
112 views

is there an equivalent of “show” steps? [duplicate]

Possible Duplicate: Get a “step by step” evaluation in Mathematica In wolfram alpha, when preforming for complicated integrals there's a 'show steps' option that explains how ...
0
votes
4answers
1k views

Specify a variable as an integer

I have a formula that always evaluates to a certain number for any variable X under one condition that X is an integer and ...
0
votes
2answers
263 views

How can I get the approximate analytical solution to this simple algebra equation?

Is there a way to get the analytical form to the root of this equation 2 A e (-ArcTanh[smax/s0] + ArcTanh[(smax Cos[w \[Zeta]])/s0]) == F0 ...
0
votes
3answers
161 views

Avoid creation of OwnValues when inserting transformation rules into Experimental`OptimizeExpression

I have a large list of transformation rules that I want to simplify. I find Experimental`OptimizeExpression works as it gets me the answers. My question is: **I can only get this to work when I ...
0
votes
4answers
158 views

Minimization in single component of BSpline to extract points

I smoothed some data with a BSpline $B[t] = (x[t],y[t])$. I would like to extract certain points from this spline by their x-Values, $x_0$. The easiest way I came up with was to minimize ...
0
votes
1answer
162 views

Plot[ D[Sin[x]] ] and Evaluate[] [duplicate]

Why does t = 2 Pi; Plot[D[Sin[x],x], {x,0,t}] (* Plotting the derivative of Sin[x] *) not work, but ...
0
votes
2answers
140 views

Symbolic evaluation fails because it exceeds $RecursionLimit

I am trying to perform a simple arithmetic in complex algebra. ...
0
votes
1answer
65 views

Why does Compile redo the calculation when overflow happens?

When implementing the Numerov method solving Schrodinger equation, I encountered this problem. In order to show the order of the evaluation, Print is added. ...
0
votes
1answer
99 views

Not evaluating all cells unless I explicitly evaluate each one?

I'm running a Mathematica (version 8) notebook. In one of the first few cells, it is supposed to plot some data. It uses a couple functions that are defined in an above cell. If I do Evaluation-> ...
0
votes
2answers
82 views
0
votes
2answers
43 views

Expand “hierarchical” system of equations

I have a system for equations that is structured hierarchically: - Level 0: these are base variables that I can measure from a process (e.g. a,b,c) - Level 1: these are variables derived from Level 0 ...
0
votes
1answer
747 views

Can graph interpolating function, but not use it. Any thoughts?

When solving a system of differential equations numerically, I get two interpolating functions. I can graph both of these, but when I try to evaluate either of the functions at a point, it just spits ...
0
votes
3answers
159 views

Evaluation in Manipulate [duplicate]

I have an expression assigned to a variable. For example: exp1 = a*x+b Now I would like to plot it using something like this ...
0
votes
1answer
651 views

Array of functions, evaluation in plot

I would like to create two arrays of functions yfunc[[i]] and tfunc[[i]], with each entry of those functions being a function ...
0
votes
1answer
118 views

NIntegrate failling on floating value

I'm trying to take the following integral NIntegrate[ ((Sin[Q 1]-Q 1*Cos[Q 1])/(Q 1)^3)^2 * S[Q,0.4,2] * Q BesselJ[0,0.5Q] , {Q,0,Infinity}] ...
0
votes
1answer
40 views

Ivar error with Fit inside Plot

I'm trying to plot this Plot[Fit[med,{1,x},x],{x,0,10}] Why this doesn't work? I find out that if I do ...
0
votes
2answers
81 views

Simplifying Fourier transform of a complicated function

I would like to evaluate the following expression but takes too much time. I would be greatly appreciate for any comments to make it fast. ...
0
votes
1answer
122 views

Getting unevaluated function expression

Say I've got a function f[x_] := a x^2 + b*x + c; and later set for some other reason a=1; how can I get the expression of f in ...
0
votes
1answer
103 views

Evaluate integral of a series

I want to evaluate this integral, but it won't work. Does anyone knows why? ...
0
votes
1answer
323 views

NumericQ prevents evaluation at a numerical value sometimes

I set up a symbolic integral, to be evaluated only when some of the symbols have been replaced by numbers. The evaluation after assigning numbers to the symbols is still symbolic for some reason. The ...
0
votes
2answers
42 views

Different behaviour of Map and Inner in replace rules

Why does x[{1, 2}] /. {x[l_] -> Map[func, l]} {1, 2} not behave as expected, while for example ...
0
votes
1answer
46 views

How to see partial results during evaluation [duplicate]

I am computing a long Table[], but the computation of the last few elements is taking too long, and I am afraid I will never converge. I would like to access the ...
0
votes
1answer
56 views

How to force numeric evaluation?

I need to evaluate the PolyLog function at some points, but I'm interested in numeric values. E.g. PolyLog[3, 2.7] works fine, but PolyLog[3, e] just prints the same PolyLog[3, e]. I somehow need to ...
0
votes
3answers
163 views

Automatically evaluate next cell

I am new to Mathematica. I am trying to achieve the following: I need one input cell in which I set parameters, then another input cell where functions are defined and calculations are performed. ...
0
votes
2answers
56 views

Evaluate differentiation after replacement

The problem is Find two linearly independent solutions of $2x^2y'' -xy' + (-4 x + 1)y = 0, \, x>0$ of the form $y_1 = x^{r_1}(1 + a_1 x + a_2 x^2 + a_3 x^3 + \cdots)$ and $y_2 = x^{r_2}(1 + b_1 x ...
0
votes
3answers
87 views

Preventing evaluation until all undefined symbols are resolved

FixedPoint[If[# <= 0, 0, # - 1]&, 2 x] Causes an infinite loop because of 'x'. How do i automatically prevent evaluation until ...
0
votes
1answer
89 views

Plot producing many error messages when given complicated function

I'm new to Mathematica and am running in to all sorts of silly difficulties with coding in it. I'm trying to calculate a function f[x, k], normalise it with another ...