Hard floats use an on-chip floating point unit. Soft floats emulate one in software. The difference is speed. It’s strange to see both used on the same target architecture, since the chip either has an FPU or doesn’t. You can enable soft floating point in GCC with -msoft-float. You may want to recompile your libc … Read more
Nothing like this exists in the C or C++ standards at present. In fact, there isn’t even a guarantee that float will be a binary floating-point format at all. Some compilers guarantee that the float type will be the IEEE-754 32 bit binary format. Some do not. In reality, float is in fact the IEEE-754 … Read more
sqrtss gives a correctly rounded result. rsqrtss gives an approximation to the reciprocal, accurate to about 11 bits. sqrtss is generating a far more accurate result, for when accuracy is required. rsqrtss exists for the cases when an approximation suffices, but speed is required. If you read Intel’s documentation, you will also find an instruction … Read more
Your instinct is basically right, sorting in ascending order (of magnitude) usually improves things somewhat. Consider the case where we’re adding single-precision (32 bit) floats, and there are 1 billion values equal to 1 / (1 billion), and one value equal to 1. If the 1 comes first, then the sum will come to 1, … Read more
IEEE 754 basics First let’s review the basics of IEEE 754 numbers are organized. We’ll focus on single precision (32-bit), but everything can be immediately generalized to other precisions. The format is: 1 bit: sign 8 bits: exponent 23 bits: fraction Or if you like pictures: Source. The sign is simple: 0 is positive, and … Read more
The operands of the binary operation 3 / 10 are untyped constants. The specification says this about binary operations with untyped constants if the operands of a binary operation are different kinds of untyped constants, the operation and, for non-boolean operations, the result use the kind that appears later in this list: integer, rune, floating-point, … Read more
Swift 2.0+ Now with Swift 2.0 you can just use Float(Wage.text) which returns a Float? type. More clear than the below solution which just returns 0. If you want a 0 value for an invalid Float for some reason you can use Float(Wage.text) ?? 0 which will return 0 if it is not a valid … Read more
In Java, when you type a decimal number as 3.6, its interpreted as a double. double is a 64-bit precision IEEE 754 floating point, while floatis a 32-bit precision IEEE 754 floating point. As a float is less precise than a double, the conversion cannot be performed implicitly. If you want to create a float, … Read more
A typical way would be to use stringstream: #include <iomanip> #include <sstream> double pi = 3.14159265359; std::stringstream stream; stream << std::fixed << std::setprecision(2) << pi; std::string s = stream.str(); See fixed Use fixed floating-point notation Sets the floatfield format flag for the str stream to fixed. When floatfield is set to fixed, floating-point values are … Read more
As no one has added it, it should be noted that going forward from Python 2.6+ the recommended way to do string formating is with format, to get ready for Python 3+. print [“{0:0.2f}”.format(i) for i in a] The new string formating syntax is not hard to use, and yet is quite powerfull. I though … Read more