/*

  Program:  TRIM.c              Revision:  13-JUNE-1997

  This program ask for you to enter three parameters:

     Value of the Trim Pot in Ohms when it is set at its maximum resistance.
     Value of the network with the Trim Pot is set at its maximum resistance.
     Value of the network with the Trim Pot is set at its minimum resistance.


                 +------+
                 |      |   POT         R1
                 |      V
                 +-----WWW-------------WWW-------+
                 |                               |
       0---------+                               +----------0
                 |                               |
                 +-------------WWW---------------+

                                R2



  Note that there is not a solution for this circuit when the required
  span of the network is greater than the value of the pot.

  Note that a circuit of this type is useful when the value of the pot
  is large compared to the required span of the network.  In this case,
  this network can give a more linear adjustment than the other option, i.e.


                 +------+
                 |      |   POT
                 |      V
                 +-----WWW------+         R1
                 |              |
       0---------+              +--------WWW------------0
                 |              |
                 +-----WWW------+

                        R2


 */


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

#define     PI       3.1415926

main ()

{
        float   pot   ;     /*  the value of the trim pot in Ohms   */
        float   max   ;     /*  the maximum value of the network, pot at full */
        float   min   ;     /*  the minimum value of the network, pot at 0 */

        float   temp_1, temp_2, temp_3, temp_4, temp_5    ;
        float   res_1,  res_2                             ;

        printf(" \n ");
        printf("Enter the trim pot value in Ohms,  the networks maximum \n ");
        printf("resistance in Ohms  and the networks minimum resistance  \n");
        printf("in Ohms.                                                 \n");
        printf(" \n ");

        printf("Enter Trim Pot resistance  (Ohms) : ");
        scanf( "%f", &pot )    ;
        printf(" \n ")          ;

        printf("         Enter the maximum network resistance  (Ohms): ");
        scanf( "%f", &max )  ;
        printf(" \n ")          ;

        printf("         Enter the minimum network resistance  (Ohms): ");
        scanf( "%f", &min )     ;
        printf(" \n ")          ;


        printf( "\n The Trim Pot is = %7.2f Ohms \n",
                pot )  ;

        printf( "\n The MAXimum network resistance is =  %7.2f Ohms \n",
                max )  ;

        printf( "\n The MINimum network resistance is =  %7.2f Ohms \n",
                min )  ;


        temp_1 =  pot * (min - max)  ;

        temp_2 =  2 * (max - min)    ;

        temp_3 =  pot * pot * ( (max * max) - (2 * min * max) + (min * min) ) ;

        temp_4 =  4 * pot * ( (min * max * max) - (min * min * max) )         ;

        temp_5 =  sqrt( temp_3 + temp_4 )                                     ;

        res_1  =  (temp_1 + temp_5)  / temp_2                                 ;


       printf( "\n The resistor in series with the pot, R1, is = %7.2f Ohms \n",
                res_1 ) ;


        res_2  =  (res_1 * min) / (res_1 - min)                               ;


       printf( "\n The resistor in parallel, R2, is = %7.2f Ohms \n",
                res_2 ) ;

}