Question

c++程序出错：缺少 类模板 "std::complex" 的参数列表

代码用来计算1维FFT
#include <iostream>
#include <complex>
#include <cmath>
#include <iterator>
using namespace std;

unsigned int bitReverse(unsigned int x, int log2n)

{
int n = 0;
int mask = 0x1;
for (int i=0; i < log2n; i++)

{
n <<= 1;
n |= (x & 1);
x >>= 1;
}
return n;
}
const double PI = 3.1415926536;
template<class Iter_T>
void fft(Iter_T a, Iter_T b, int log2n)
{
typedef typename iterator_traits<iter_t>::value_type complex;
const complex J(0, 1);
int n = 1 << log2n;
for (unsigned int i=0; i < n; ++i) {
b[bitReverse(i, log2n)] = a[i];
}

for (int s = 1; s <= log2n; ++s)

{
int m = 1 << s;
int m2 = m >> 1;
complex w(1, 0);
complex wm = exp(-J * (PI / m2));
for (int j=0; j < m2; ++j)

{
for (int k=j; k < n; k += m)

{
complex t = w * b[k + m2];
complex u = b[k];
b[k] = u + t;
b[k + m2] = u - t;
}
w *= wm;
}
}
}
int main( )

{
typedef complex cx;
cx a[] = { cx(0,0), cx(1,1), cx(3,3), cx(4,4),
cx(4, 4), cx(3, 3), cx(1,1), cx(0,0) };
cx b[8];
fft(a, b, 3);
for (int i=0; i<8; ++i)
cout << b[i] << "\n";

}

vs2012 编译出错
关键错误信息为

10 IntelliSense: 缺少 类模板 "std::complex" 的参数列表 c:\Study\GEOS6393\Assignment\2\code\my\fftcpp\fftcpp\fft.cpp 57 9 fftcpp
对应这一行 typedef complex cx;
求解答啊~~~~~~

Answer 1

模板必须带类型参数
不能单独出现complex，必须complex<TYPE>