The first column in the file (EEG1) is the signal obtained for an electroretinog
ID: 3598873 • Letter: T
Question
The first column in the file (EEG1) is the signal obtained for an electroretinogram, ERG (differential voltage, from right(+) to left(-) lower eye lids, in micro-Volts)
The second column (EEG2) is the activity of the visual cortex or Visual Evoked Potential, VEP (Fz(-) to Cz(+), also in micro-Volts)
The third column (STIM) is the stimulus trigger signal. A non-zero value for the trigger signal means that a stimulus was delivered at that time, and signifies time=0 for that sweep.
There are a total of m = 261 stimulus presentations, or sweeps. Fs = 2000 Hz. The two signals EEG1 and EEG2 are measured in micro-Volts, which means multiply them with 10^-6 to translate to Volts.
I HAVE THE values of EEG1 and 2 and STIM but i dont know how to upload them
Write a MATLAB code that will allow you to:
1) Observe improvements in signal quality as you average more sweeps i.e. signal obtained from each stimulus. For example, start with averaging EEG1 and EEG2 signals in response to the first 2 sweeps (DO NOT Average EEG1 and EEG2 together, just the sweeps within each variable. These represent the response at two separate points in the visual pathway (Retinal level and Visual cortex level). As you average more, and the response is revealed, you will notice differences in peak times which are representative of the conduction time along the visual pathway (Cortical responses have later peak times or latencies due to this being further down the visual path. Make two separate plots (Subplots on one figure) of the averaged electroretinogram and visual cortex signals. Next average 10 sweeps, 20, 50, 100 and maximum available sweeps. For each sweep count, create a separate figure with subplots showing the ERG and VEP
at those sweep levels. Explain what you observe (This can be done with text on the .fig or .PDF of the figures).
Explanation / Answer
package com;
import java.util.ArrayList;
public class ArrayWithExponentAsIndexPolynomial implements PolynomialInterface
{
int polynomial[];
int highExp;
ArrayWithExponentAsIndexPolynomial()
{
polynomial=new int[200];
}
ArrayWithExponentAsIndexPolynomial(String pol)
{
polynomial=new int[200];
highExp=0;
int co=0;//Coefficient
int exp=0;//exponent
//Convert the polynomial string into linked list of polynomial terms
for(int i=0;i<pol.length();i++)
{
co=0;
exp=0;
//Find coefficient
while(pol.charAt(i)!='x' && pol.charAt(i)!='X' )
{
if(pol.charAt(i)=='-')
{
i++;
while(i<pol.length())
{
if(pol.charAt(i)!='x' && pol.charAt(i)!='X' )
{
String sub=pol.substring(i,i+1);
co=co*10+Integer.parseInt(sub);
}
else
break;
i++;
}
co=co*-1;
}
else if (pol.charAt(i)=='+')
{
i++;
}
else
{
String sub=pol.substring(i,i+1);
co=co*10+Integer.parseInt(sub);
i++;
}
if(i>=pol.length())
break;
}
i++;//skip x
if(i==pol.length())
{
if(pol.charAt(i-1)=='x' || pol.charAt(i-1)=='X')
exp=1;
}
i++;//skip ^
if(i<pol.length())
while(pol.charAt(i)!='-' && pol.charAt(i)!='+' )
{
String sub=pol.substring(i,i+1);
exp=exp*10+Integer.parseInt(sub);
i++;
if(i>=pol.length())
break;
}
if(highExp<exp)
highExp=exp;
addATerm(exp,co);
i--;
}
}
// stores the coefficient at index(exp)
void addATerm(int exp,int co)
{
// store the coefficient at index(exp)
polynomial[exp]=co;
}
int getHigh()
{
return highExp;
}
@Override
//Adds two polynomials and returns the resultant polynomial
public PolynomialInterface add(PolynomialInterface other)
{
int high;
ArrayWithExponentAsIndexPolynomial temp=new ArrayWithExponentAsIndexPolynomial();
ArrayWithExponentAsIndexPolynomial otherPoly=(ArrayWithExponentAsIndexPolynomial)other;
if(this.getHigh()<otherPoly.getHigh())
{
high=otherPoly.getHigh();
temp.highExp=otherPoly.getHigh();
}
else
{
high=this.getHigh();
temp.highExp=this.getHigh();
}
for(int i=0;i<=high;i++)
{
if(this.polynomial[i]!=0 && otherPoly.polynomial[i]!=0)
{
temp.polynomial[i]=this.polynomial[i]+otherPoly.polynomial[i];
}
else if (this.polynomial[i]==0 && otherPoly.polynomial[i]!=0)
{
temp.polynomial[i]=otherPoly.polynomial[i];
}
else if (this.polynomial[i]!=0 && otherPoly.polynomial[i]==0)
{
temp.polynomial[i]=this.polynomial[i];
}
}
return temp;
}
@Override
//Substracts one polynomial from another and returns the resultant polynomial
public PolynomialInterface subtract(PolynomialInterface other)
{
int high;
ArrayWithExponentAsIndexPolynomial temp=new ArrayWithExponentAsIndexPolynomial();
ArrayWithExponentAsIndexPolynomial otherPoly=(ArrayWithExponentAsIndexPolynomial)other;
if(this.getHigh()<otherPoly.getHigh())
{
high=otherPoly.getHigh();
temp.highExp=otherPoly.getHigh();
}
else
{
high=this.getHigh();
temp.highExp=this.getHigh();
}
for(int i=0;i<=high;i++)
{
if(this.polynomial[i]!=0 && otherPoly.polynomial[i]!=0)
{
temp.polynomial[i]=this.polynomial[i]-otherPoly.polynomial[i];
}
else if (this.polynomial[i]==0 && otherPoly.polynomial[i]!=0)
{
temp.polynomial[i]=0-otherPoly.polynomial[i];
}
else if (this.polynomial[i]!=0 && otherPoly.polynomial[i]==0)
{
temp.polynomial[i]=this.polynomial[i];
}
}
return temp;
}
public String toString()
{
String poly="";
//Convert the linked list into polynomial string
for(int i=this.getHigh();i>=0;i--)
{
if(polynomial[i]!=0)
{
if(i==1)
{
if(polynomial[i]<0)
poly=poly+"-"+polynomial[i]*-1+"x";
else
poly=poly+polynomial[i]+"x";
}
else if(i!=0)
{
if(polynomial[i]<0)
poly=poly+"-"+polynomial[i]*-1+"x^"+i;
else
{
if(i!=this.getHigh())
poly=poly+"+"+polynomial[i]+"x^"+i;
else
poly=poly+polynomial[i]+"x^"+i;
}
}
else
{
if(polynomial[i]<0)
poly=poly+"-"+polynomial[i]*-1;
else
poly=poly+"+"+polynomial[i];
}
}
}
return poly;
}
}
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.