math.h

问题 Using Visual Studio Express2013 for Windows Desktop, with a "Win32 Console Application" C++ project (I'm doing a project for a course. In order to start, I have to import all of the project files that the instructor provided - there are tons (all .cpp and .h files), so I can't really copy-paste any of them here... but I don't think that's the issue anyway). When I hit "run debugger," I get nearly 200 syntax errors in math.h Even though math.h is what came with Visual Studio. All the errors

问题 Through unfortunate circumstances I have discovered that my standard library implementations <math.h> and <cmath> (C++) apparently contain a definition for a function with a prototype like: double gamma(double x); Though I do not see it listed anywhere in the language standard (draft I have access to). Using gcc v4.2.1 on Mac OS X that function evaluates the same as tgamma which is actually the name given to it in the standard. (reference) But on gcc v4.6.3 on Ubuntu 12.04 that function

问题 Yesterday I asked a floating point question, and I have another one. I am doing some computations where I use the results of the math.h (C language) sine, cosine and tangent functions. One of the developers muttered that you have to be careful of the return values of these functions and I should not make assumptions on the return values of the gcc math functions. I am not trying to start a discussion but I really want to know what I need to watch out for when doing computations with the

问题 I'm having some trouble trying to compile a program that uses exp function on Ubuntu. I get this error from gcc: selied@Apolo:~/Dropbox/practicas UAM/Neuro/practica3$ make gcc -lm -o retropropagacion retropropagacion.o retropropagacion.o: In function `main': /home/selied/Dropbox/practicas UAM/Neuro/practica3/retropropagacion.c:177: undefined reference to `exp' /home/selied/Dropbox/practicas UAM/Neuro/practica3/retropropagacion.c:186: undefined reference to `exp' /home/selied/Dropbox/practicas

问题 So I am working with some matlab code converting to c code by hand. I am just wondering if there is a c equivalent to the sind and cosd functions I'm seeing in the matlab code. I guess this returns the answer in degrees rather than the c sin and cos function that gives the result in radians. I guess I could just multiply the result by 180/pi but was just wondering if there was a library function in math.h I'm not seeing. Or even if there is something in the gsl library that does that. 回答1:

问题 In an app I'm profiling, I found that in some scenarios this function is able to take over 10% of total execution time. MSVC++ 2008 compiler is being used, for reference... I don't recall if modf maps to a single instruction or if there is likely any way to make it faster. see also here for similar question on sqrt function Unlike sqrt, I don't really know how modf works. Is there an assembly operation? For instance you could do: modf(float input,int &intPart, float &floatPart) { intPart=

问题 (This is my first question ever on StackOverflow) I have to use a Mac at work, and I'm coding in C++ with Code::Blocks (because I am used to this IDE). 2 days ago I upgraded from MacOS High Sierra to MacOS Mojave and I can fairly say that... it was a bad decision. Now, when trying to #include <math.h> I get this error : fatal error: sys/cdefs.h: No such file or directory . I have tried to reinstall the xcode line command tools with xcode-select --install , but it still doesn't work. Does

问题 when I try to compile this simple code from terminal: #include<stdio.h> int main(void) { printf("%f\n",sqrt(10)); return 0; } using gcc main.c command, it gets compiled and a.out gives correct answer. It means that that maths functions are added in C standard library which gets linked automatically. But if compile the same code in Eclipse IDE without adding any library to properties, it gives undefined reference error. It means maths functions are not part of C standard library. What is the

问题 Hello i am using linux 12.04 and geany for coding. The code i am writing in C worked completely fine until i used the sqrtf command to find the square root of a float. Error: HAC3.c:(.text+0xfd7): undefined reference to `sqrtf' . The part of code i am using sqrtf: float syn(float *a, float *b, int dimensions) { float similarity=0; float sumup=0; float sumdown=0; float as=0; float bs=0; int i; for(i=0; i<dimensions; i++) { sumup = sumup + a[i] * b[i]; as = as + a[i] * a[i]; bs = bs + b[i] * b

问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 7 years ago . I am inputting a number n where 1<=n<=10^5. I need a number of length n. So I use pow(10,n-1) but it doesnt work when n=100000. What is the error ? EDIT: Its codeforces div2 round 152 problem B. Chilly Willy