I'm trying to use Taylor series to develop a numerically sound algorithm for solving a function. I've been at it for quite a while, but haven't had any luck yet. I'm not sure what I'm doing wrong. The function is f(x)=1 + x - sin(x)/ln(1+x) x~0 Also: why does loss of precision even occur in this function? when x is close to zero, s...
So I've gotten the answer to my last question (I don't know why I didn't think of that). I was printing a double using cout that got rounded when I wasn't expecting it. How can I make cout print a double using full precision? Thanks ...
I am responding to MouseLeftButtonDown events on elements added to a WPF canvas. It all works fine when clicked (i.e. the eventhandler fires off correctly), but it requires too much precision from the mouse pointer. You have to be perfectly on top of the circle to make it work. I need it to be a little more forgiving; maybe at least 1 or...
In C#. I have a double (which I've extracted from a database) that has 20 digit precision. In Visual Studio (using QuickWatch) I can see the value of the double to be = 0.00034101243963859839. I want to display this value in a textbox and then have it be the same value when I take it out and convert it back into a double. But I alway...
I am really confused how to compute precision and recall in clustering applications. I have the following situation: Given two sets A and B. By using a unique key for each element I can determine which of the elements of A and B match. I want to cluster those elements based on features (not using the unique key of course). I am doing ...
I have a long double constant that I am setting either as const or not-const. It is longer (40 digits) than the precision of a long double on my test workstation (19 digits). When I print it out, it no longer is displayed at 19 digits of precision, but at 16. Here is the code I am testing: #include <iostream> #include <iomanip> #incl...
I have a function getSlope which takes as parameters 4 doubles and returns another double calculated using this given parameters in the following way: double QSweep::getSlope(double a, double b, double c, double d){ double slope; slope=(d-b)/(c-a); return slope; } The problem is that when calling this function with arguments for examp...
Consider the following C# code: double result1 = 1.0 + 1.1 + 1.2; double result2 = 1.2 + 1.0 + 1.1; if (result1 == result2) { ... } result1 should always equal result2 right? The thing is, it doesn't. result1 is 3.3 and result2 is 3.3000000000000003. The only difference is the order of the constants. I know that doubles are impl...
After one hour of trying to find a bug in my code I've finally found the reason. I was trying to add a very small float to 1f, but nothing was happening. While trying to figure out why I found that adding that small float to 0f worked perfectly. Why is this happening? Does this have to do with 'orders of magnitude'? Is there any workar...
In my C++ program, I need to pull a 64 bit float from an external byte sequence. Is there some way to ensure, at compile-time, that doubles are 64 bits? Is there some other type I should use to store the data instead? Edit: If you're reading this and actually looking for a way to ensure storage in the IEEE 754 format, have a look at Ada...
Can a double (of a given number of bytes, with a reasonable mantissa/exponent balance) always fully precisely hold the range of an unsigned integer of half that number of bytes? E.g. can an eight byte double fully precisely hold the range of numbers of a four byte unsigned int? What this will boil down to is if a two byte float can hol...
So, I know a little bit about how floating point are represented, but not enough to be sure of my answer. The general question: for a given precision (for my purposes, the number of accurate decimal places in base 10), what range of numbers can be represented for 16-, 32-, and 64-bit IEEE-754 numbers? Specifically, I'm only interested ...
Hi every body! I have a code, and I do not understand it. I am developing an application which precision is very important. but it does not important for .NET, why? I don't know. double value = 3.5; MessageBox.Show((value + 1 * Math.Pow(10, -20)).ToString()); but the message box shows: 3.5 Please help me, Thank you. ...
I'd like to know if there is a way to improve the accuracy of calculating a slope. (This came up a few months back here). It seems by changing: float get_slope(float dXa, float dXb, float dYa, float dYb) { return (dXa - dXb)/(dYa - dYb); } to float get_slope(float dXa, float dXb, float dYa, float dYb) { return dXa/(dYa - d...
I was wondering if anyone knew of a better sleep function that could be used in windows in c, other than Sleep(), which takes a millisecond input and only guarantees that the input is the minimum amount of time that elapses. I am passing in 1 millisecond, but actually getting a 15-16 millisecond delay. Is there any way to accurately set ...
So I know about floating point precision (and how things like 1.1 can't be expressed exactly in binary) and all that, but I'm wondering: how then, do math-related libraries implement infinite precision? In other words, how would you represent, for example, 1.1 accurately in binary? Just a brief description would be great, I can figure ou...
I did some testing with floating point calculations to minimize the precision loss. I stumbled across a phenomen I want to show here and hopefully get an explanation. When I write print 1.0 / (1.0 / 60.0) the result is 60.0024000960 When I write the same formula and do explicit casting to float print cast(1.0 as float) / (cast(1...
Assuming you have a machine instruction udive that does a special case 64 by 32 unsigned division by taking a (32bit dividend << 32) / 32bit divisor, we can do a full 64 by 32 division using the following: // assume: a / b guaranteed not to overflow a = 64bit dividend, a.h & a.l are hi & lo 32bits respectively b = 32bit divisor q1 = ud...
I try to store the PHP floating point value 63.59072952118762 into a double precision column in postgres. Postgres stores the value as 63.59073. Does anyone know why? 8 byte should be more than enough for that value. I've tried with the data type numeric, which works when specifying the precision, but that shouldn't really be necessary. ...
I'm working with fractions using Python's decimal module and I'd like to get just the repeating part of a certain fraction. For example: if I had 1/3 I'd like to get 3, if I had 1/7 I'd like to get 142857. Is there any standard function to do this? ...