MapLine function assistance requested

hi i am really struggling with writing a function called mapline i have started but seem to be getting knowhere if anyone could help it would be greatly appreciated. the info given is

write a function that takes a curve x:j ->R^n and a map M:R^n -> R^n and returns the image y of x under M, given by the graph y:j ->R^n, y(s)= M(x(s)). the first line of the function is 

function [y,snew] = MapLine(M,x,maxdist,maxangle)

so far i have

function [y,snew] = MapLine1(M,x,maxdist,maxangle)

G=0;
m=0;
spreads=length(G);
sharps=zeros(m);

[n,N]=size(x);
y(s)=M(x(s));
snew=s;

j=[s(1),s(end)];

for i=1:N 
    x(:,i)=x(s(i));
    y(:,i)=M(:,i);
end

now there are meant to be two refinements in there (one to inser points when the distance is to large and the other when the angle is too sharp) but all i really need is how to start this off and i think i can get the rest.

any help would be great.