void praying_calc(uint16_t days){
    /* to calculate and return time of all praying, */
    
    uint8_t hight;    
    float length_line_mid, length_line_real, length_line_diff, width_circle;

    float* data;
    float cita;
    float equoftime;
    float delta;
    float duhur, shorok, ghroup, fagr, ishaa;
    float numerator;
    float denominator;
    
    
    length_line_mid  = 30;
    hight             = 23;        
    width_circle     = 30;        
    length_line_real = 31.13;    
    
    
    length_line_diff = length_line_mid - length_line_real;
    
    data = EOT(days);  //calculate and return Equation of Time and delta 
    equoftime = data[0];
    delta     = data[1];
    
    cita  = 90.8309 + 0.0353 * sqrt(hight) ;
    numerator   = cos(cita * M_PI/180) - sin(width_circle*M_PI/180) * sin(delta*M_PI/180);
    denominator = cos(30*M_PI/180) * cos(delta*M_PI/180);
    
    duhur  = 12.0 + length_line_diff / 15.0 - equoftime / 60.0; // الظهر
    shorok = duhur - acos(numerator/denominator)*180/M_PI/15;   // الشروق
    ghroup = duhur + acos(numerator/denominator)*180/M_PI/15;   // المغرب
             
    numerator   = cos((cita+18) * M_PI/180) - sin(width_circle*M_PI/180) * sin(delta*M_PI/180);
    fagr  = duhur - acos(numerator/denominator)*180/M_PI/15;  // الفجر
    ishaa = duhur + acos(numerator/denominator)*180/M_PI/15;  // العشاء

}