C代码 放到STM32上 求大佬帮助

Question

#include<stdio.h>
#include<math.h>
#include<stdlib.h>
#define N 1024 
typedef struct{
	double real;
	double imag;
}complex;
complex x[N], *W;
int size=1024;
double l[5000],h[5000];
double PI=4.0*atan(1);
void output()
{
	int i;
	for(i=0;i<size;i++)
	{	
		printf("%lf  %lf  %.4f",h[i],l[i],x[i].real);
		if(x[i].imag>=0.0001)
		{
			printf("+%.4fj\n",x[i].imag);
		}
		else if(fabs(x[i].imag)<0.0001)
		{
			printf("\n");
		}
		else
		{
			printf("%.4fj\n",x[i].imag);
		}
	}
}
void change()
{
	complex temp;
	unsigned short i=0,j=0,k=0;
	double t;
	for(i=0;i<size;i++)
	{
		k=i;
		j=0;
		t=(log(size)/log(2));
		while( (t--)>0 )
		{
			j=j<<1;
			j|=(k & 1);
			k=k>>1;
		}
		if(j>i)
		{
			temp=x[i];
			x[i]=x[j];
			x[j]=temp;
		}
	}
}
void transform()
{
	int i;
	W=(complex *)malloc(sizeof(complex) * size);
	for(i=0;i<size;i++)
	{
		W[i].real=cos(2*PI/size*i);
		W[i].imag=-1*sin(2*PI/size*i);
	}
}
void add(complex a,complex b,complex *c)
{
	c->real=a.real+b.real;
	c->imag=a.imag+b.imag;
}
void sub(complex a,complex b,complex *c)
{
	c->real=a.real-b.real;
	c->imag=a.imag-b.imag;
}
void mul(complex a,complex b,complex *c)
{
	c->real=a.real*b.real - a.imag*b.imag;
	c->imag=a.real*b.imag + a.imag*b.real;
}
void fft()
{
	int i=0,j=0,k=0,m=0;
	complex q,y,z;
	change();
	for(i=0;i<log(size)/log(2) ;i++)
	{
		m=1<<i;
		for(j=0;j<size;j+=2*m)
		{
			for(k=0;k<m;k++)
			{
				mul(x[k+j+m],W[size*k/2/m],&q);
				add(x[j+k],q,&y);
				sub(x[j+k],q,&z);
				x[j+k]=y;
				x[j+k+m]=z;
			}
		}
	}
}
int main()
{
	int i;
	double fs=1000;
	double t[5000];
	for(i=0;i<size;i++)
	{
		t[i]=i/fs;  
		x[i].real=3+2*cos(2*PI*850*t[i])+3.6*cos(2*PI*300*t[i])+2.6*sin(2*PI*400*t[i])+5.5*cos(2*PI*200*t[i]+PI/2)+3.8*sin(2*PI*80*t[i]);//+4*cos(2*PI*150*t[i]+PI/2)+16*sin(2*PI*50*t[i]);//输入连续时间信号，并对其进行采样
		x[i].imag=0;
		h[i]=i*(fs/(double)size);
	}
	transform();
	fft();
	for(i=0;i<size;i++)  
	{
		l[i]=sqrt(x[i].imag*x[i].imag+x[i].real*x[i].real) ;
	}
	printf("输出FFT后的结果\n");
	output();
	return 0;
}

改一下变量名 让其能在STM32上运行 

刚开始学 怎么都弄不出来，麻烦了 salute

Answer 1

是报的什么错误

line 12: atan 这个funtion 能找到吗