% Remember to try your answers on your OWN command line! If it doesn't
  work for you, it's unlikely to work for Cody. If you misspell the
  name of a function, you better catch it yourself!


W4Q1: Find a median

This wasn't half as tricky as you may have thought. Turns out that the
PRCTILE function is not available under Cody. Hence I asked for the
50th percentile, which is the median!

% My solution
v=1:100;
w=linspace(0,1,length(v));
vw=v.^w;
vp=median(vw);

% This might have been correct if Cody had the STATS toolbox:
vp=prctile(vw,50);


W4Q2: Make a histogram

% Most of you had absolutely no problem with this one
v='FREDERIK';
va=abs(v);
vh=hist(va,4);
vl=max(vh);


W4Q3: Calculate a correlation

% Same here, most people had this very thing  without any trouble
x1=[ 1  5 -6  8  9  2 0 -2 18 29 54];
x2=[-1  4 -6  4 12 -2 3 -2 33 19 47];
R=corrcoef(x1,x2);
r=R(2);


W4Q4: Fit a polynomial

% The important lesson here is that any number N of data can be
  exactly represented by a polynomial of degree N-1, i.e. by an
  INTERPOLATING polynomial, which will then hit all the requested
  values without any error. 

% My solution
x=[ 1     2     3     4     5     6     7     8];
y=[70    82    69    68    69    82    73    75];
N=length(x);
P=polyfit(x,y,length(x)-1);
yval=P(1)*x(1)^7+...
     P(2)*x(1)^6+...
     P(3)*x(1)^5+...
     P(4)*x(1)^4+...
     P(5)*x(1)^3+...
     P(6)*x(1)^2+...
     P(7)*x(1)^1+...
     P(8)*x(1)^0;
r=abs(y(1)-yval);


% Some people tried to use a function called RESID. That being an
  incredibly high-level and sophisticated function - impossible to
  apply correctly unless you really read up on it. 

% Some tried to stick in the value
r=0
% which, obviously, cheats the test. Not allowed!

% Some of you got lucky with
r=yval-y(1);
% but really, the question and your query should be about the ABSOLUTE
residual! 


W4Q5: Evaluate a polynomial

% My solution
P=[17/280 -271/144 5743/240 -23209/144 49433/80 -12028/9 622691/420 -619];
Pd=length(P)-1;
x=1:8;
Px=polyval(P,x);
Pc=char(round(Px)+64);

% Some people tried the function COUNT instead of LENGTH, which I
  didn't know, but isn't the right thing for this problem.

% It might have been a giveaway that the correct answer spelled my own
  name. Those of you who had 'FREDERI' but not 'FREDERIK' should have
  caught it yourselves.