LCD display : NaN

Hi,



I have a problem of displaying the output data on LCD. it will display "NaN", which i have read that this is not a data. This problem arises when i start to acquire data from the sensors (meaning when there is reading). But if the sensors circuit are off and the reading is zero, there is output data. i think it could be due to integer to floating point conversion of the aquired data. i have tried several times by changing the data types but the output is still display :NaN. But if i do normalize the data in (1 to -1)there will be an output reading. If i dont normalize the data, the output reading will be in around 1000 to 8000 . The problem arises when i am not normalizing the data.



Here is the code.

 #include <stdio.h>
#include <math.h>
#include <reg51.h>
//#include <AT89X52.h>
#include <stdlib.h>
//#include <intrins.h>

.......
/*Main Program*/
main()
{
	int pmax=10,i,n=8,j;
	int data_LSB,data_MSB,CH[10];
    int CHn[10],min=2,max=1;
    ppi_set();
    serial_init();


 for (i=0;i<=pmax;i++)						//for number of pulse <=10
    {
	 if (PULSE==1)							//Check whether PULSE =1
	 {
	    for (j=0;j<8;j++)					//If yes do DAQ of 8 Ch (0-7)
		   {
			 P1=j;							//Write Add to Port 1 (0-7)
			 data_LSB=PA;					//Read LSB data from Port A
			 data_MSB=PB;					//Read MSB data from Port B
			 CH[j]=(data_MSB<<8)|data_LSB;  //Shift Left MSB data 8 times ("|"is bitwise 'or' to sum both bit)
			 printf("%d\t",CH[j]);
            // min=(min<CH[j])? min:CH[j];	//Scan for Min data
			// max=(max>CH[j])? max:CH[j];	//Scan for Max data
			 }
	    printf("\n");
        for (j=0;j<n;j++)
		   {
		//	CHn[j]=2*((CH[j]-min)/(max-min))-1; //Data Normalization formula make data in range (-1,1)
		    CHn[j]=(float) CH[j];    //Raw data (in range 1000-8000)

           }

		ANN(n,CHn);		//Call ANN process function

		 }
        wait(1);
       }


}

/*ANN PROCESS*/

#include <stdio.h>
#include <math.h>
#include <intrins.h>
/* External LCD output function*/
extern void LCD(float O[]);

/*ANN Function Definitioan*/
void ANN(int n,float CHn[])

{	int j,h,hmax=6,o,omax=4;  //Hidden Neuron (hmax)=6, Output Neuron(omax)=4
    float xdata O[5],H[8];
	float xdata WHI[6][8]= {//WHI=Weight value of connection between Input=8 and Hidden=6

		/*Weight with logsig and logsig transfunction*/
		{2.7294,4.5239,-0.0103,-0.6089,4.8868,-5.7313,-2.6335,0.4967},
		{-4.7325,-3.8315,-0.1689,-1.6844,8.3110,4.7062,0.1422,-1.3525},
		{3.1464,2.3160,0.6550,0.6286,3.3174,0.9235,8.5057,0.6745},
		{2.6970,-3.2395,-0.7225,-4.6076,5.4900,-7.1220,0.5794,2.2767},
		{4.4916,1.7946,0.4944,0.5825,0.7911,-9.6612,-4.7229,-0.1789},
		{1.6326,-4.5621,-4.2867,-0.9461,-2.9762,-3.0127,-0.6397,-1.7811}

	};

	float xdata WOH[4][6]= {//WOH=Weight value of connection between Hidden=6 and Output=4

		/*Weight with logsig and logsig transfunction*/
		{10.2251,3.9513,2.6186,8.5117,3.7212,-7.4772},
		{-5.0325,-9.1396,-1.4935,13.1217,-0.5011,5.5292},
		{4.3388,-13.4855,3.0468,-10.0947,6.0913,-8.8211},
		{-9.7137,9.8602,-1.9421,-2.2828,-8.7116,1.1900}

	};

	float xdata BH[6]={//BH=Bias of Hidden Neuron=6

		/* Bias with logsig and logsig transfunction*/
		{-6.4229},{10.9651},{-3.3755},{-2.2552},{-6.6035},{-2.6723}};

	float xdata BO[4]={//BO=Bias of Output Neuron=4

		/* Bias with logsig and logsig transfunction*/
    	{-15.1368},{-8.9549},{3.7160},{-0.3211}};

	for (h=0;h<hmax;h++)//Multiply and Accumulate Input*Weight(WHI)
	{
	  H[h]=0;
		for(j=0;j<n;j++)
		{
			H[h]=H[h]+(CHn[j]*WHI[h][j]);  // do the Multiply for hidden first

		}

			H[h]=H[h]+BH[h];	    		//Accumulate with Bias of each Hidden
			H[h]=1.0/(1.0+exp(-1.0*(H[h])));//Logsig Transfer Function
	}


	for (o=0;o<omax;o++)//Multiply and Accumulate Hidden Output*Weight(WOH)
	{
		O[o]=0;
		for(h=0;h<hmax;h++)
		{
			O[o]=O[o]+(H[h]*WOH[o][h]);	//Multiply for output neuron

		}
            O[o]=O[o]+BO[o];		   // Accumulate with Bias of each Output neuron
		    O[o]=1.0/(1.0+exp(-1.0*(O[o])));//Transfer function logsig

	  }

	LCD(O); // Call LCD Gas output display function


}
/* LCD output display of detected gas*/
/* Display Result of Neuron Output using sprintf()*/
/**************************************************************************************/
....
/* Main Program Function : LCD DISPLAY*/

void LCD(float O[])
{  //data int i;
   char buf[40];
   ppi_set();//Configures the PPI :PA & PB as input, PC as Output
   LCD_init ();



  /* Check on each neuron Output value, if>0.9 display the detected GAS*/

          sprintf(buf,"O[0]:%f",O[0]);
          LCD_StringCentered (1,buf);
	     // sprintf(buf,"O[1]:%f",O[1]);
         // LCD_StringCentered (2,buf1);
          wait(30000);





}

Please help to find out why it keep displaying NaN. Your help is much appreciated.

Thanks