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44
votes
3answers
1k views

When I can assume that all decimal digits returned by Mathematica are provably correct?

How to Control the Precision and Accuracy of Numerical Results Arbitrary-Precision Numbers Mathematica works with exact numbers and with two different types of approximate numbers: ...
21
votes
3answers
494 views

Real Numbers in the Wolfram Language

Epilog: Much of the discussion in the answers below revolves around the distinction between Real as a data type and real numbers as a domain or class of numbers (irrespective of the form in which ...
19
votes
6answers
1k views

Formatting a fraction as a mixed number

Is there a command that will take a rational number and rewrite it in a mixed-number-like form? That is, I'd like to apply a command to something like 10/7 and get ...
16
votes
5answers
757 views

Is this the most efficient way to round approximate integers to integers while leaving other Reals untouched?

This might seem like an overly simple question, but I need to specify custom plot tick marks as integers (no trailing decimal point) if they are approximately integers, but not if they are not. Using ...
13
votes
4answers
2k views

How to implement Donald Knuth's up-arrow notation

How does one enter very large numbers in up-arrow notation? Up-arrow notation was created by Donald Knuth to write very large numbers in it iterated exponentiation form, for example 6↑↑3 = 6^6^6.
10
votes
1answer
580 views

Number format in Legend Labels

I would like to use the usual (new and nice) BarLegend[] with something like BarLegend[{"LakeColors", 1/10000 {-2, 2}}] which ...
9
votes
3answers
688 views

Expression of uncertainty in measurement.

I have a problem with writing a Mathematica function. I have been requested to show the results of my experiments with the measurement uncertainty (mu) like below: ...
8
votes
4answers
1k views

How to plot logarithmic scales

How can a simple logarithmic number line be drawn between any 2 integer values? The closest function I found in the documentation is LogLinearPlot[] and I've ...
8
votes
2answers
1k views

Convert a string to hex number?

How can I convert a string containing a hex number such as "6b" to a hex digit that mathematica can use to do math with? I have tried using ...
8
votes
1answer
1k views

How do I get Mathematica to show a number in non-exponential form? [duplicate]

Sometimes I make a calculation in Mathematica that produces a big number, which Mathematica shows like so: -1.52522*10^7 This is annoying to me, because I want ...
7
votes
1answer
2k views

Entering numbers in Scientific Notation?

I need to play with a lot of powers such as 10^-3. 1E-3 does not work for it. Is there any short form for it?
6
votes
7answers
185 views

Join decimal part

I have a list of mesures that each vector is like {0,1,-2,259} but it should be like {0.1,-2.259} So I did a rule, like ...
6
votes
1answer
172 views

Machine Epsilon

I'm trying to evaluate the machine epsilon of my computer (see below). I wrote this: ...
5
votes
2answers
437 views

Fast Karatsuba Squaring, how to?

I want to improve timing of squaring for big numbers. So I asked What is the fastest way to split a number into parts and What is the most efficient way to add zeros to end of a number with several ...
5
votes
2answers
1k views

Converting numbers to integers

I've read the available documentation but I still haven't found an NumberForm -> Integer function yet. No result in this site's search, either. Does it exist? ...
5
votes
2answers
123 views

Display All Output Numbers in HEX

How might I modify Mathematica such that I can get the following functionality when working with HEX values. The odd lines are input and the even output. Red values should be the HEX values. ...
5
votes
0answers
122 views

NMinimize seems to call function with the same values multiple times

I have to minimize a function where the evaluation of one parameter set takes very long (around 5sec) and discovered alongside, that NMinimize seems to call this ...
5
votes
1answer
177 views

Is it possible to lower the bitwidth of (floating point) numbers?

The answer to this question will most probably be a definite no. Nevertheless, I would like to know whether it is possible to represent reals in the memory on less than the standard 32 or 64 bits ...
4
votes
3answers
177 views

What is the FullForm of 36^^sadjh.87s567*^-34?

The Mathematica parser parses and computes number literals before sending them to FullForm even if Hold is applied. Thus the ...
4
votes
3answers
183 views

How can I improve NumberString?

I would like to test strings to see if they represent numbers. This should include number representations with precision marks and scientific notation. NumberString ...
4
votes
2answers
367 views

What is the most efficient way to add zeros to end of a number?

Beside *10^n, is there a faster way to add thousands of zeros to end of a number? Updated Timings: ...
4
votes
2answers
119 views

Showing AlgebraicNumber[1/2 (1 + Sqrt[5]), {-3, 2}] in human-readable way

Is there a function to show algebraic numbers in Mathematica more conveniently? I am looking for something similar to MatrixForm for matrices. For example, I would like to view ...
3
votes
3answers
264 views

Customizing decimal mark used in plot frame tick labels

I am using the Plot function in a usual way. I use Mathematica 9.0.1.0 in English (I do not know if it is available in other languages, but I do not mind), and as a ...
3
votes
2answers
583 views

hexList[[1]] returns a list of decimal numbers

Sorry for not being clear about this question earlier. I appreciate the answers I got, but the edits I made should make the question more understandable. I have been working with hex in ...
3
votes
1answer
99 views

Is there a `Real` equivalent to `FromDigits`?

One can extract an Integer's digits using IntegerDigits and reassemble them into the Integer ...
3
votes
2answers
426 views

Representation of negative exponents [duplicate]

Possible Duplicate: Way to improve “show me this decimal number to M places, don't use scientific notation”? How can I expand e.g. number 1.*10^-8 so that there would be no ...
2
votes
2answers
549 views

decompose a number (less than 255) in a sum of powers of 2

Is there a built in function that would take a number and decompose it into a sum of powers of 2? The numbers will be non negative less than 256. For what it's worth I'm trying to understand a paper ...
2
votes
3answers
95 views

Testing for a vector of reals [closed]

Suppose I define: RealVector[expr_]:=VectorQ[expr,NumberQ[#]&&Head[#]===Real)]; Then: ...
2
votes
1answer
61 views

Range and decimal digits [duplicate]

When I set Plot[Sin[x], {x, -2, -1}, Frame -> True, Axes -> False, FrameTicks -> {{Automatic, Automatic}, {Range[-2, -1, 0.2], Automatic}}] I ...
2
votes
2answers
377 views

Enter exact rational numbers easily with decimal notation

Is there a simple way to enter decimal numbers such as 0.123 so that Mathematica interprets it as an exact rational number 123/1000?
2
votes
2answers
93 views

How to interpret and show an input number with the amount of significant digits given?

what can I do to have Mathematica intepret and show a number with exactly the amount of digits I gave as an input? I have a larger talbe with numbers (text file, whitespace seperated) which are ...
1
vote
2answers
76 views

Arithmetic on algebraic numbers

I'd like to perform some elementary operations on algebraic numbers. ...
1
vote
2answers
139 views

create a function that converts a character string consisting of lowercase letters of the english alphabet to a number

I need a function that will take input as a string of lowercase letters and then output integers in this form a=01 b=02 c=03 d=04 e=05 . . . z=27 The letters must correspond with these integers ...
1
vote
1answer
674 views

Change number from real to integer [duplicate]

Possible Duplicate: Is this the most efficient way to round approximate integers to integers while leaving other Reals untouched? Please consider the following: ...
1
vote
1answer
86 views

How can I export numerical data in a calculation-favorable format?

I am exporting some data into the txt file but since the values exported to this txt file expresses 10^6 to be *^6, I cannot use these numbers in calculations in other programs.. For instance, when I ...
1
vote
1answer
70 views

How to get only the real solutions of an equation? [closed]

Is there any simple way to get only the real solutions of the eq. x^3-1=x? I've tried: Solve[x^3-1==x,x] But it gives the complex ones, too. I have Mathematica ...
1
vote
1answer
72 views

Avoid unnecessary truncation

Is there any way to change the general settings in Mathematica so that when I type e.g. 0.34*60000000 I get the output ...
1
vote
1answer
202 views

Number with no decimal mark

I'm using Mathematica to create some images and labeling them after a simple calculation done previously. As the name of the file depends on the result, I want to show it with no decimal separator ...
1
vote
1answer
251 views

What is the fastest way to split a number into parts?

I have very large numbers (million digits). number = A*10^partlen + B As of now, I split the numbers by this way: ...
1
vote
0answers
50 views

How can I perfect this game for Wolfram Demonstration publication? [closed]

When the messages change the window inactivates, and when I try to host an interactive CDF on my site it turns red and says something about numbers having to be scaled or offset. Any help? I'm ...
1
vote
0answers
125 views

How to work with large numbers

How do I browse very large numbers in mathematica, say $10^{{10}^{{10}^{1.414\ldots}}}$? By browse I mean finding the $k$th decimal place before or after the decimal point. Everything I have tried ...
0
votes
1answer
72 views

Why does my function return an expression rather than a number? [closed]

I feel like I'm going insane. I have a function $f(x)=e^{-x^2}$ which I need to evaluate using forward, backward and central first order finite differences with intervals ...
0
votes
2answers
132 views

The precision of the number

I have problem in Mathematica with unnecessary rounding which is caused by high precision. For example I have value a = 2.052685846*10^-1865, when I make ...
0
votes
3answers
73 views

Is there a global setting for number form

Im creating strings which represent equations in C to use with library link. The problem i have is that numbers in scientific form, when converted to strings, are no longer useful. e.g. ...
0
votes
1answer
144 views

Converting strings of the form “1.34e5” to real numbers? [duplicate]

ToExpresssion doesn't understand real numbers of the form "1.34e5". How do I convert the string ...
0
votes
1answer
63 views

Square root of a value defined in a finite field?

I am trying to find the right way to compute the square root of a number defined in a finite field. For example, ...
0
votes
2answers
62 views

Function that returns the binary string given its index in lexicographic ordering

Index the binary strings in lexicographic order, so that the empty string " " corresponds to 0, the string "0" corresponds to 1, the string "1" to 2, and so on. I want a function that, given a ...
0
votes
1answer
37 views

How to “de rationalize” a number? [closed]

How can 1/2 be represented as 0.5? Thanks!
0
votes
1answer
137 views

Finite precision - how to get rid of “near zeros” [duplicate]

I am performing a finite-precision operation on a matrix A which I know precisely; call the result B. The operation is taking ...
0
votes
0answers
48 views

Balanced n-ary Base Representation

This may be a repeat question, but I was wondering how one would implement the expression/calculation of a representation of a given number h in base balanced n-ary, where n>1 is odd. (For example, ...