This feels like the kind of code that only fails in-situ, but I will attempt to adapt it into a code snippet that represents what I'm seeing. float f = myFloat * myConstInt; /* Where myFloat==13.45, and myConstInt==20 */ int i = (int)f; int i2 = (int)(myFloat * myConstInt); After stepping through the code, i==269, and i2==268. What's ...
Hi, the players: 64bit linux with php 5 (ZendFramework 1.10.2) PostgreSQL 8.3 Doctrine 1.2 Via a Flash/Flex client i get an 8byte integer value. the field in the database is an BIGINT (8 byte) PHP_INT_SIZE show that system supports 8byte integer. printing out the value in the code as it is and as intval() leads to this...
I had used several ways to do some simple integer arithmetic in BASH (3.2). But I can't figure out the best (preferred) way to do it. result=`expr 1 + 2` result=$(( 1 + 2 )) let "result = 1 + 2" What are the fundamental differences between those expressions? Is there other ways to do the same? Is the use of a tool like bc mandatory f...
How do I calculate a curve of a linear floating point number (0 to 1) and get another floating point number as a result? What I want is up until the half (0..0.5), to be inversed logarithmic and high than that to be logarithmic like a curve according to the given linear value. ...
In the stdint.h (C99), boost/cstdint.hpp, and cstdint (C++0x) headers there is, among others, the type int32_t. Are there similar fixed-size floating point types? Something like float32_t? ...
I'm using MSVC++, and I want to use the special value INFINITY in my code. What's the byte pattern or constant to use in MSVC++ for infinity? Why does 1.0f/0.0f appear to have the value 0? #include <stdio.h> #include <limits.h> int main() { float zero = 0.0f ; float inf = 1.0f/zero ; printf( "%f\n", inf ) ; // 1.#INF00 print...
What are the different techniques for a floating point type to an integer type conversion, in c++? ...
We were discussing this the other day at work and I wish there was a Stackoverflow question I would point people at so here goes.) What is the difference between a Double and a Decimal? When (in what cases) should you always use a Double? When (in what cases) should you always use a Decimal? What’s the driving factors to consider in ca...
I am doing some performance critical work in C++, and we are currently using integer calculations for problems that are inherently floating point because "its faster". This causes a whole lot of annoying problems and adds a lot of annoying code. Now, I remember reading about how floating point calculations were so slow approximately cir...
I want to test if a number double x is an integer power of 10. I could perhaps use cmath's log10 and then test if x == (int) x? edit: Actually, my solution does not work because doubles can be very big, much bigger than int, and also very small, like fractions. ...
What determines the default setting of the x87 FPU control word -- specifically, the precision control field? Does the compiler set it based on the target processor? Is there a compiler option to change it? Using Microsoft Visual C++ 2008 Express Edition on an Intel Core Duo processor, the default setting for the precision control field...
Newbie here. I have the following code: myADC = 128 maxVoltage = 5.0 maxADC = 255.0 VoltsPerADC = maxVoltage/maxADC myVolts = myADC * VoltsPerADC print "myADC = {0: >3}".format(myADC) print "VoltsPerADC = {0: >7}".format(VoltsPerADC) print VoltsPerADC print "myVolts = {0: >7}".format(myVolts) print myVolts This outputs the following...
HI, I am trying to use the robust predicates for computational geometry from Jonathan Richard Shewchuk. I am not a programmer, so I am not even sure of what I am saying, I may be doing some basic mistake. The point is the predicates should allow for precise aritmthetic with adaptive floating point precision. On my computer: Asus p...
I ran into an issue by introducing floating point columns in the MySQL database schema that the comparisons on floating point values don't return the correct results always. 1 - 50.12 2 - 34.57 3 - 12.75 4 - ...(rest all less than 12.00) SELECT COUNT(*) FROM `users` WHERE `points` > "12.75" This returns me "3". I have read that the ...
It's 123.98699999999999 ! Why is that? Thanks guys! :) ...
Hi, I am coding up an implementation of Interpolation Search in C. The question is actually rather simple, I need to use the floating operations to do linear interpolation to find the correct index which will eventually be an integer result. In particular my probe index is: t = i + floor((((k-low)/(high-low)) * (j-i))); where, i,j,...
Is converting Fixed Pt. (fixed n bit for fraction) to IEEE double safe ? ie: does IEEE double format can represent all numbers a fixed point can represent ? The test: a number goes to floating pt format then back to it's original fixed pt format. ...
Double has range more than a 64-bit integer, but its precision is less dues to its representation (since double is 64-bit as well, it can't fit more actual values). So, when representing larger integers, you start to lose precision in the integer part. #include <boost/cstdint.hpp> #include <limits> template<typename T, typename TFloat>...
I am trying to perform broad-phase collision detection with a fixed-grid size approach. Thus, for each entity's position: (x,y,z) (each of type float), I need to find which cell does the entity lie in. I then intend to store all the cells in a hash-table and then iterate through to report (if any) collisions. So, here is what I am doing...
EDIT: I had made a mistake during the debugging session that lead me to ask this question. The differences I was seeing were in fact in printing a double and in parsing a double (strtod). Stephen's answer still covers my question very well even after this rectification, so I think I will leave the question alone in case it is useful to s...