/*

  Program:  David.c              Revision:  18-AUG-1995

  This program ask for you to enter three parameters:
     Frequency in Mhz
     Inductance in uH
     Capacitance in pF

  Enter the majic value of  "0"  for one of these parameters.  This program
  will then calculate the value of that parameter and display it.

  The unknow value is calculated by the high Q parallel resonant frequency
  (by one definition) equation:

                   1                 or solve                    1
      F =  ------------------        for C          C =  ----------------
            2 pi  sqrt( LC )         and it is           4  pi^2  F^2  L


  and recall that the inductive reactance is:

      Inductive Reactance = 2 pi f L

 */


#include <stdio.h>
#include <math.h>

#define     PI       3.1415926

main ()

{
        float   freq, cap, induct         ;
        float   two_pi, four_pi_sqrd      ;
        float   reactance                 ;

        two_pi  =  2.0 * PI               ;
        four_pi_sqrd  =  two_pi * two_pi  ;

        printf(" \n ");
        printf("Enter the resonant frequency, the inductance, and the \n "    );
        printf("capacitance.  Enter  0  for the unknow value of the three. \n");
        printf(" \n ");

        printf("Enter the resonant frequency (MHz) : ");
        scanf( "%f", &freq )    ;
        printf(" \n ")          ;

        printf("         Enter the inductance (uH): ");
        scanf( "%f", &induct )  ;
        printf(" \n ")          ;

        printf("        Enter the capacitance (pF): ");
        scanf( "%f", &cap )     ;
        printf(" \n ")          ;


        if ( freq == 0 ) {

            freq  =  1000.0 / ( 2.0 * PI * sqrt( induct * cap ))  ;

            printf( "\n This parallel LC resonant freq. is = %9.3f MHz \n",
                   freq )  ;

            reactance = two_pi * freq * induct   ;

            printf( "\n The reactance of either L or C is  =  %7.2f Ohms \n",
                   reactance )  ;
            }


        else if ( induct == 0 ) {

            induct = 1000000.0 / (four_pi_sqrd * (freq * freq) * cap)  ;

            printf( "\n The inductance from Freq and cap is = %7.2f uH \n",
                   induct ) ;

            reactance = two_pi * freq * induct   ;

            printf( "\n The reactance of either L or C is  =  %7.2f Ohms \n",
                   reactance )  ;
            }


        else if ( cap == 0 ) {

            cap = 1000000.0 / (four_pi_sqrd * (freq * freq) * induct )  ;

            printf( "\n The capacitance from Freq and L is = %7.2f pF \n",
                   cap ) ;

            reactance = two_pi * freq * induct   ;

            printf( "\n The reactance of either L or C is  =  %7.2f Ohms \n",
                   reactance )  ;
            }
}