sqrt:domain error,该怎么解决

sqrt:domain error
#   include   <math.h>
#define   L   0.02
#define   R   1.0
main()
{
  float   C,frequen;
  frequen   =   sqrt(1/(L*C)-R*R/(4*C*C));
  printf   ( "\n ");
  for   (C=0.01;C <=0.1;C+=0.01)
  printf   ( "%f\n ",frequen);
}

运行就是五行0.000000
然后再来个sqrt:domain   error
这是怎么回事啊?

[解决办法]
frequen = sqrt(1/(L*C)-R*R/(4*C*C)); //这里面的C使用前没初始化
[解决办法]
LS说的对啊~~
调一下顺序就行了，呵呵~~~
#include <math.h>
#define L 0.02
#define R 1.0
main()
{
float C,frequen;
printf ( "\n ");
for (C=0.01;C <=0.1;C+=0.01){
frequen = sqrt(1/(L*C)-R*R/(4*C*C));
printf ( "%f\n ",frequen);
}
}