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### The /. syntax in numerical methods [duplicate]

I have an analytical approximation method for solving an ODE and want to compare this to an NDSolve solution, but the syntax is confusing me. To get the solution from NDSolve, I define the ODE as eqn ...
119 views

### StringJoin Dynamic problem [duplicate]

My goal is to import a XML file from the site fueleconomy.gov to get a list of cars dependent on the year given as the user input . Here is the code: ...
69 views

### Use pattern as Assumptions: How to properly extend working pattern? [duplicate]

I am struggling with an extension of using a working pattern used as Assumptions for Simplify and the like. Consider this: <...
86 views

### Part function: can we use pattern for part functions? [duplicate]

Can we use some patterns for the arguments of Part functions? ...
84 views

### Separation of output [duplicate]

I have solved two equations with two unknowns and confined my answer in just ten answers. The unknowns are n and k, and I want ...
102 views

### Creating sublists [duplicate]

I got this example in Mathematica references. v = ToExpression["a" <> ToString[#]] & /@ Range[1,44] Could someone explain to me the function of the ...
61 views

### Evaluation of m.v is blocked by applying MatrixForm. Why? [duplicate]

I'm trying to understand what is happening in the notebook session below. I have a 2x2 matrix m = {{-1,-1}, {-1,-1}}. And a vector ...
59 views

### Deciphering Coding Shortcuts [duplicate]

I'm having trouble deciphering why the following couple of expressions evaluate the way they do. #&@@ This returns the first value of a list. Why? Naïvely I ...
123 views

### Plot not displaying [duplicate]

I'm trying to perform a basic plot to show that two equations align, but I'm not getting any results. Plot[{[Pi]*Cos (3 x - [Pi]), [Pi] * Sin (3*[Pi] - 3 x)}, {x, -3 [Pi], 3 [Pi]}] To me this seems ...
120 views

### Stop function evaluating input at time of definition [duplicate]

I would like to create a function that acts on whether the input is even or odd, e.g.: In[644]:= f[a_] = If[EvenQ[a], 2 a, 3 a]; f[2] Out[645]= 6 I've ...
90 views

### Use Manipulate to visualize how roots of a system of equations changes with parameters - SOLVED [duplicate]

I am editing this question, I hope to be able to respect the rules. My goal is to find the roots of a system of 6 nonlinear equations (they are actually more, this is a simplified version). The roots ...
89 views

### NMaximize not substutiting parameters of objective function [duplicate]

NMaximize is not substituting parameters of its objective function. Is there a way to fix that? I have a three line program that exhibits the problem. ...
84 views

### Mathematica returns unsolved integral [duplicate]

I have the following integral: ...