OK, just to inform you guys, I finally made it. Seems like there is support for storing float type data in Flash. All you have to do is store it:
PROGMEM float Theta[]={1,2,3,4...};
and read it out:
float a;
a =(float) pgm_read_float(&Theta[i]); // i can be some constant or counter
Thank you all, cheers.