cmath

问题 I have this assignment in which i will show the prompt for it: Write a program that reads in a set of test score data from the user. (Test scores should be entered in decimal form to represent the percentage grade). Once the user has finished entering the test scores (entering -1 will signal the end of input), print out the number of tests entered, the average of the tests, and the standard deviation. Use the following formula (Welford’s method) to calculate the standard deviation: (Standard

问题 I'm trying to learn C++ and I'm using MS Visual Studio 2019. I have the code below: #include <iostream> int main() { std::cout << pow(10, 2); } How is it possible to compile and run without error without including cmath ? Inside the solution there is only one file with the above code. 回答1: How is possible in C++ to use pow without include cmath library By including another header that includes the <math.h> header. There is no guarantee that standard library headers won't include other headers

问题 I'm trying to learn C++ and I'm using MS Visual Studio 2019. I have the code below: #include <iostream> int main() { std::cout << pow(10, 2); } How is it possible to compile and run without error without including cmath ? Inside the solution there is only one file with the above code. 回答1: How is possible in C++ to use pow without include cmath library By including another header that includes the <math.h> header. There is no guarantee that standard library headers won't include other headers

问题 I'm trying to compile a program on Windows using MingW (msys2) and it fails with the j0 function. On Linux it compiles no problem. It seems to hate when I use the -std=c++11 flag on the compiler. How can I get this to compile properly and with the -std=c++11 flag on? Sample code: #include <cmath> int main( int argc, char *argv[] ) { float test = j0( 5 ); } Output $ g++ -std=c++11 test.cpp -o test test.cpp: In function 'int main(int, char**)': test.cpp:6:21: error: 'j0' was not declared in

问题 My code: import math import cmath print "E^ln(-1)", cmath.exp(cmath.log(-1)) What it prints: E^ln(-1) (-1+1.2246467991473532E-16j) What it should print: -1 (For Reference, Google checking my calculation) According to the documentation at python.org cmath.exp(x) returns e^(x), and cmath.log(x) returns ln (x), so unless I'm missing a semicolon or something , this is a pretty straightforward three line program. When I test cmath.log(-1) it returns π i (technically 3.141592653589793j ). Which is

问题 I am getting some very confusing results when using the fmod function. The following code: double x = pow(142, 35); double y = fmod(x, 221); std::cout << x << std::endl << y; outputs: 2.13842e+75 206 But when hard coding the x value: double x = pow(142, 35); double y = fmod(2.13842e+75, 221); std::cout << x << std::endl << y; The output is changed to: 2.13842e+75 14 I have no idea what the cause of this is, and it is creating some ugly bugs within my program. Any insight would be greatly

问题 Given the following user-defined type S with a conversion function to double : struct S { operator double() { return 1.0;} }; and the following calls to cmath functions using the type S : #include <cmath> void test(S s) { std::sqrt(s); std::log(s); std::isgreater(s,1.0); std::isless(s,1.0); std::isfinite(s) ; } This code compiles with gcc using libstdc++ ( see it live ) but with clang using libc++ it generates errors for several of the calls ( see it live ) with the following error for

问题 I am writing a C++ class which represents an arithmetic type (a c++ wrapper around mpfr), and I'd like to support some functions found in <cmath> (I'll take std::sqrt as an example). So I have the following class: namespace ns { class MyClass { /* ... */ public: friend MyClass sqrt(const MyClass& mc); }; } And I can use it this way: MyClass c; /* ... */ MyClass d = ns::sqrt(c); MyClass e = sqrt(c); // Apparently I don't have to specify ns:: But I cannot use it this way: MyClass f = std::sqrt

问题 I have a data set of complex numbers, and I'd like to be able to find parameters that best fit the data. Can you fit data in complex numbers using leastsq as implemented by scipy in python? For example, my code is something like this: import cmath from scipy.optimize import leastsq def residuals(p,y,x): L,Rs,R1,C=p denominator=1+(x**2)*(C**2)*(R1**2) sim=complex(Rs+R1/denominator,x*L-(R1**2)*x*C/denominator) return(y-sim) z=<read in data, store as complex number> x0=np.array[1, 2, 3, 4] res =

问题 The final committee draft of the upcoming C++0x standard says: Every C header, each of which has a name of the form name.h, behaves as if each name placed in the standard library namespace by the corresponding cname header is placed within the global namespace scope. It is unspecified whether these names are first declared or defined within namespace scope (3.3.6) of the namespace std and are then injected into the global namespace scope by explicit using-declarations (7.3.3). Earlier C++