java - variable showing strange value when implementing NLMS algorithm in Android -

i have been scratching head day , have run out of ideas now, posting here

i trying implement feedback suppressor in android using nlms algorithm
use audiorecord obtain audio samples mic , audiotrack play back. read in 1 sample @ time short variable, convert double, pass through algorithm, convert short , send speaker. however, getting weird values in intermediate variable , canot understand why happening. here code:

public class mainactivity extends activity {     audiomanager = null;     audiorecord record =null;     audiotrack track =null;     final int sample_frequency = 16000; // original 44100     final int size_of_record_array = 1;     // 1024 original; 1000 / 40 = 25     // final int wav_sample_multiplication_factor = 1;     final double wav_sample_multiplication_factor = 0.5;     final int n = 4; // original 40     final int feedback_delay_in_msec = 1;   // use small integer values here keep calculation of no_of_delay_samples becoming non-whole number     // final int no_of_delay_samples = sample_frequency / (feedback_delay_in_msec * 1000); // no_of_delay_samples = 16     final int no_of_delay_samples = 0;      final int total_size_of_x = n + no_of_delay_samples;     int = 0, n = 0; // n represents nth sample     boolean isplaying = false; // represents if pass through button pressed     boolean applydsp = false; // represents if apply filter button pressed     boolean bufferfull = false;     private volatile boolean keepthreadrunning;     double[] w = new double[n];     // w represents filter coefficients     double[] x = new double[total_size_of_x];     double e;      double d;     double send_out;     double mu;     double y = 0;      // /*     private randomaccessfile statefile;     string statefileloc = environment.getexternalstoragedirectory().getpath();     filedescriptor fd;     // */      class mythread extends thread{         private volatile boolean needstopassthrough;         // /*         mythread(){             super();         }          mythread(boolean newptv){             this.needstopassthrough = newptv;         }         // */          // /*         @override         public void run(){             short[] lin = new short[size_of_record_array];             short[] speaker = new short[size_of_record_array];             double speaker_double;             int num = 0;             log.d("mylog", "entered run");             if(needstopassthrough){                 record.startrecording();                 track.play();                 log.d("mylog", "comes here before btn press?");             }                         n = total_size_of_x -1;             while (keepthreadrunning) { // thread runs until loop stops; loop runs long program running                 num = record.read(lin, 0, size_of_record_array);                 for(i=0;i<lin.length;i++)                     d = (double)lin[i];         // line requires lin[] has single element array                  if(isplaying){                     if(applydsp){                         y=0.0; // initialize every time                         for(i=0; i<n; i++){                            y += w[n-1-i] * x[n-i - no_of_delay_samples];                         }                          // implementing step 2                         e = d - y;                          // /*                         try {                             statefile.writedouble(e);                         } catch (ioexception e) {                             // todo auto-generated catch block                             e.printstacktrace();                         }                          // implementing step 3                         mu = 0.5 / (x[n] * x[n] + 0.01);                          // implementing step 4                         for(i=0; i<n; i++){                                w[n-1-i] = w[n-1-i] + 2.0*mu*e*x[n-i - no_of_delay_samples];                         }                     } // closing of if(applydsp) block                      // implementing step 5                         for(i=0;i<total_size_of_x-1;i++){                             x[i] = x[i+1];                         }                      send_out = e;                        speaker_double = send_out * wav_sample_multiplication_factor;                      // implementing step 6                     x[total_size_of_x -1] = speaker_double;                      for(i=0;i<speaker.length; i++)                         speaker[i] = (short)speaker_double;                      track.write(speaker, 0, num);                 } // if(isplaying) block closed; represents if "pass through" button has been clicked              } // while (keepthreadrunning) closes here; infinite loop runs long program running              record.stop();             track.stop();             record.release();             track.release();         }          public void stopthread(){             keepthreadrunning = false;         }      } // end of mythread class      mythread newthread;   

i have included part of code contains thread performs nlms keep short. since size_of_record_array 1, lin variable in num = record.read(lin, 0, size_of_record_array); short array 1 element. (in fact, anu double or short array may encountered in above code have single element). line e = d - y key here. d value mic (d short typecasted double). during every run of while (keepthreadrunning) { infinite loop, new value e should calculated, later typecasted short , passed audiotrack. problem e not getting proper values in case, , there no output speakers. if send variable d audiotrack, whatever input spoken in microphone appears @ output (with slight delay, expected). if try write e variable values file, getting strange values. since using string.valueof(e) did not work out me (each string character considered 16-bit character , 0 appears <space>0, -1 appears <space>-<space>1), directly wrote double value file using randomaccessfile.write double , viewed file in hex viewer. seems there random value @ beginning of file, after pattern emerges, not sure why there. screenshot of hex file shown below:

the pattern shown continues till end of file. why happening? since there no output assumed @ least should have been 0, can seen figure it's not 0 either, instead 7f f8 00 00 00 00 00 00 repeated again , again. please me determine why happening.

ps: boolean values isplaying , applydsp represent state of 2 buttons have on interface. when press applydsp button on interface, speaker makes short , relatively loud "pop" sound, assume may reason random values in beginning of file containing values of e shown above, not sure this, , not sure abput why popping noise there in first place.