For loope small increments

I cannot seem to find the solution to this problem. I write a for loop and i tell it to increment by a small value, but instead of starting at 1, it starts at 2.9110 here is the loop

for m=1:.001:4

      m
  end

does anyone know what its going on? i expect it to start at 1 and increment by .001 every time so that it goes 1.001, 1.002, 1.003 and so on thank you

Answer 1

[Matt Fig]

I don't know why you think this starts at 2.910. Perhaps you are running into the limit of your command window when trying to scroll back up after running the loop. Do this:

for m=1:.001:4
    m
    pause(.5)
end

Now you should see m incrementing like you expect as it prints slowly out.

[Paulo Silva]

Matt that code might freak out someone who doesn't know how to stop it (CTRL+C in MSWIN OS)

[Matt Fig]

True, but I thought everyone know about ctrl+c!

Answer 2

[Paulo Silva]

It works fine here, try this

m=1:.001:4;

What's the first value of the vector m?

Answer 3

[marvin corado]

yes matt you are right, since the answer was printed in the command window and it always started at 2.910, but when i add the puase it starts at 1 and increments as i expect. thankfully i did know about ctrl_c :)

Answer 4

[marvin corado]

ok but my problem seems to be something else then because my code is supposed to increment M starting at 2 and increment it .0001 up to 3. here is my code

f=0.006;
M= 3;
gamma = 1.4;
L_D=50;
Mx=1;
tol=1e2;

for Mx=2:.0001:3

      a =(1-(M^2))/(gamma*M^2);
      b = (gamma+1)/(2*gamma);
      c = ((gamma+1)*(M^2))/(2+((gamma-1)*M^2));
      %friction parameter coefficient for m1
      Fp1 = a+(b*log(c));
      %guessing 
      %friction parameter coefficient for guess
      a1 =(1-(Mx^2))/(gamma*Mx^2);
      b1 = (gamma+1)/(2*gamma);
      c1 = ((gamma+1)*(Mx^2))/(2+((gamma-1)*Mx^2));
      Fpx = a1+(b1*log(c1));
      %Lx = L1star-Lxstar
      Fpg=Fp1-Fpx;
      %doing table A2 Normal shock
      num=1+(((gamma-1)/2)*Mx^2);
      den= (gamma*Mx^2)-((gamma-1)/2);
      my= sqrt(num/den);
      %friction parameter coefficient normal shock
      a2 =(1-(my^2))/(gamma*my^2);
      b2 = (gamma+1)/(2*gamma);
      c2 = ((gamma+1)*(my^2))/(2+((gamma-1)*my^2));
      Fpy = a2+(b2*log(c2));
      %checking Lx+Ly* = L
      X1=Fpg+Fpy;
      R=4*f*L_D;
end
if abs(X1-R)<tol
    z=Fpy   
    a=Fpg
       a1=a/(4*f)
end
break

but that if statement does not happen for 2:.0001:3 but it happens for 2.5:.0001:3 do you guys know what is going on? thank you

[Matt Fig]

Please select a best answer for this question, then start a new one. That way people can search Answers for a specific issue they are having.

Answer 5

[marvin corado]

should i start a new one? with my question above?

[Matt Fig]

Yes, that way we keep one Question per topic.