Questions on correct (or improved) formulation of Mathematica code to achieve particular results. Use this tag (not "symbol") for questions about all those odd @@ /@ # & and ~ characters.
1
vote
2answers
142 views
Write a function that returns the logarithmic derivative
How can we write a function that if we input an expression f, it returns the log derivative $\frac{1}{f} \frac{df}{dx}$. We have to use a conditional or pattern test so that the function accepts any ...
1
vote
1answer
135 views
Differentiation w/o assiging concrete values
v = Subscript[v, 0]*Sin[(Pi*S)/Subscript[S, 0]];
a = dv/ds v;
a = D[v, s]
returns
...
1
vote
3answers
144 views
More than one expression in the Table[] command?
I would like to construct a Matrix using the Table[] command. The issue is that I would like to use more than one expression for it. What I need to obtain is something like this :
...
1
vote
1answer
277 views
Why is Euler's number an uppercase “E” and not a lowercase “e”?
Why is Euler's number an uppercase "E" and not a lowercase "e"?
Isn't Euler's Number normally expressed with a lowercase "e"?
1
vote
2answers
150 views
Translating a “Point-to-Triangle” distance script from MATLAB to Mathematica
Update - Thanks everyone for your responses! After fixing a problem with vector normalization, the code below now works.
I'm a new user, and I was attempting to port some Mathematica code from ...
1
vote
1answer
96 views
Working of Date[]
Date[] returns the current date of local system, Date[1] returns {2012, 11, 15, 17, 41, 0.3161629}, ...
1
vote
1answer
75 views
Syntax for integrating over limits specified by a Table
I wish to use NIntegrate to compute multidimensional integrals. However, I don't want to manually input the limits for the dimensions. I want to store the ...
1
vote
1answer
99 views
How does one specify Neumann conditions for NDSolve?
I have a series of functions defined in my notebook, and then want to use this to solve a diffusion-reaction type equation. At the moment, something like this works:
...
1
vote
1answer
178 views
Can I use Table without the appropriate bounds?
I´d like to use the Table command without defining n, so that I can have a list of n ...
1
vote
1answer
140 views
Syntax error: newline character interpreted as multiplication
I'm getting this error in Wolfram Workbench, and I don't know where it comes from: "Syntax error: newline character interpreted as multiplication"
This error happens around an If[] function, in a ...
1
vote
1answer
135 views
Solve this equation symbolically
I am trying to solve the equation for the quantity r = y/x symbolically:
3/y^4 == 3/x^4 + a/(x + 2 y)^4
with the requirement that we need to perform the ...
1
vote
1answer
142 views
Remove failed Solve[] attempts
I can't figure how to replace a failed evaluation with a null value.
I am very new to Mathematica.
I have an equation that are being processed using the Solve[] ...
1
vote
2answers
199 views
How to insert an expression in a Mathematica program?
I need to insert a very large expression in a Mathematica program. So I first
Put[large expression,"file"]
and then use
Block[{}, Get["file"];...]
to ...
1
vote
1answer
59 views
When is Evaluate needed within function arguments? [duplicate]
I'm trying to do a simple variable substitution within a ContourPlot, but it's not working. Here's an example:
...
0
votes
2answers
149 views
Why function cannot be defined inside For loop? [closed]
I have a following code (which is simplified version of what I am doing):
For[i = 1, i <= 5, i++,
f[x_] := Sin[x]^2
Print[{i, f[i]}]
]
And the question ...
0
votes
1answer
223 views
What does the slash-colon symbol do?
I came across a bit of code that uses the syntax /: and I don't know what it does. I can't find its documentation, or maybe I'm just not looking properly. The code ...
0
votes
1answer
96 views
0
votes
1answer
104 views
What is wrong with this Cobweb plot [closed]
Something is wrong with my cobweb plot code but I couldn't figure out where do the mistakes come from.
So basically we have the iterative map $x_n == x_{n-1}^{2} - 3 \mu$. I would like to draw a ...
0
votes
1answer
77 views
Mathematica command for type checking?
I have a program where users can enter mathematica commands that can evaluate to any of the standard numeric types (complex, real, int, etc.), or to boolean values. Moreover the users can enter ...
0
votes
2answers
60 views
Getting value of clock [duplicate]
I have the following code:
a = Dynamic[Floor[Clock[2]]] (*So this basically alternates between 0 and 1*)
If[a==1, Print["true"]]
But this doesn't work, it ...
0
votes
1answer
79 views
How to tell Mathematica to make assumptions? [duplicate]
Say I want to integrate 1/(x^2+a^2) and I want Mathematica to know that $a>0$. What would be the command? Something like:
...
0
votes
1answer
101 views
0
votes
1answer
128 views
0
votes
0answers
81 views
Why doesn't Dot work on typeset vectors?
When I try to do scalar product of vectors I get the following message:
Is there a specific way to input the vectors? I'm doing it as the Basic Math Assistant palette suggests, typing {, Ctrl+,, } ...
0
votes
0answers
51 views
How to programmatically comment out multiple source files?
How to programmatically comment out the entire content of multiple .m source files assuming they start with correct Mathematica syntax? I need it to be robust so ...
0
votes
1answer
63 views
Why does Eigenvalues[matrix I defined] not work? [duplicate]
This is the code I have in my mathematica notebook. I want to find the eigenvalues of the matrix I created called Hmatrix as defined below. However when I type Eigenvalues[Hmatrix] I get the Hmatrix ...
0
votes
0answers
164 views
Derivatives in scripts [closed]
I have consistently been harrowed by this tiny issue.
When I Try to run my Mathematica script, I get this error message:
...
