Description:
Mathematica discussion group. (Moderated)
|
|
|
skipping some i, j , ... values in Table
|
| |
Hi,
Suppose I need a list, Flatten[Table[something[i,j],{ i,10},{j,10}]], where some combinations of indices i and j are voluntarily missing under a known condition (for example, stupid I know, when i+j is a prime).
How can I do that ?
Thanks in advance,
ahautot
|
|
|
writing real numeric data to file in scientific form
|
| |
I think what you are looking for is FortranForm[]. I use it exclusively now.
Here is writing it out and reading it back...
m=ToString@FortranForm[0.00000 3]
ToExpression[StringReplace[m," e-"-> "*10^"]]
If you write your data to CSV format, it can be read back in with Scientific notation without issue. CSV format really rocks with Mathematica. I still use ToString@FortranForm[] for formatting prior to writing to CSV. On read, you will get numbers back and don't need the second line above.... more »
|
|
|
Comment about SetDirectory[]
|
| |
I have often wondered whether to use:
SetDirectory[NotebookDirectory []]
Export["TestResultTime.txt", mTimeDiff, "Table"]
or
Export[NotebookDirectory[] <> "TestResultTime.txt", mTimeDiff, "Table"]
I have left Mathematica open for 2 days as it was running a very long test. Maybe something became corrupted. The first method did not work. It appears SetDirectory[] simply stopped functioning. Personally, I think the second method is better since it is atomic in nature. It doesn't depend on any stateful settings.... more »
|
|
|
2x2 determinant bug in math 9.0.0.0
|
| |
Hi all,
caution if you compute matrix determinants in Mathematica 9.0.0.0! You'll find below a 2x2 matrix composed of symbolic rational fractions. Compare Det[M] and the expected expression M[[1, 1]] M[[2, 2]] - M[[1, 2]] M[[2, 1]] . To your surprise, you'll find different results if you use Mathematica 9.0.0.0. Affected versions are independent of Linux/Mac/Win OS:... more »
|
|
|
Overriding the single quote (')
|
| |
The Verilog "programming" language provide a compact way to describe and work with digital circuits. The language features a nifty syntax for representing bits. For example 3'b101 is the 3 bit unsigned binary number 101. 3'd5 is the same binary number but represented as the decimal 5.
I wanted to set up an expression in Mathematica such as f[3'b101] rather than the more verbose f["3'b101"].... more »
|
|
|
How do you control evaluation when using apply?
|
| |
Hello,
both of your versions work fine in M9.
Here is even a shorter one:
In[]:= jacFun[func_, vars_] :=
Module[{f}, f = Function @@ {{x, y}, D[func, {vars}]};
f @@ # &]
In[]:=jacFun[{Sin[x y], Cos[x + y]}, {x, y}][{10, 2}]
Out[]:={{2 Cos[20], 10 Cos[20]}, {-Sin[12], -Sin[12]}}... more »
|
|
|
How do you control evaluation when using apply?
|
| |
Why does this work
In[0]: = jacobianFunction[func_, vars_List] := Module[{f},
f = Function[Evaluate[vars], Evaluate[D[func, {vars}]]];
f
];
jacobianFunction[{Sin[x y], Cos[x + y]}, {x, y}] @@ {10, 2}
out[0]:= {{2 Cos[20], 10 Cos[20]}, {-Sin[12], -Sin[12]}}
But this does not (the goal is to make the function take a point as an... more »
|
|
|
can't get InputField to work inside a While command
|
| |
I need to be able to input parameters for an a-priori indeterminate number of cases. The way I've been trying to do this is by using a While statement containing InputFields, one of which asks if there are to be more cases to deal with. If not, the previously True logical 'test' for While is reset to False.... more »
|
|
|
FindMinimum convergence criteria
|
| |
FindMinimum has four convergence tests, controlled by two parameters: AccuracyGoal and PrecisionGoal.
The documentation says:
* The settings for AccuracyGoal and PrecisionGoal specify the number
of digits to seek in both the value of the position of the minimum,
and the value of the function at the minimum.... more »
|
|
|
