Round off errors

• x1=[1:1e5];
  x2=[1e5:-1:1];
  y1=1./x1;y2=1./x2;
  S1=sum(y1);S2=sum(y2);format long;
  S1
  S2
  

• k=[-18:.01:-3];
  
  x=10.^k;
  
  a=((exp(x)-1)./x);plot(a);
  
  b=((exp(x)-1)./(log(exp(x))));
  
  plot(k,a,r');hold on
  
  plot(k,b,'b');hold on
  

•   x=2;k=[-20:.3:4];d=10.^k;
    e=log10(abs(cos(x)- (sin(x+d)-sin(x))./d));
    plot(k,e,'ro');
  

• x = [-5e-16:1e-18:5e-16]; y = (( 1- (1-x))./x);plot(x,y,'or')