SW's Mathematica book is quite old. Take a look at his newer book which is available online. For a more in-depth understanding of WL look at Leonid Shifrin's book, also available online.

Mr. Namjoshi: I have uploaded part of the code. If you can find the time, please take a look. (1) The problem starts with the solution of the equation in In[16] whose output is as in In[17]. (2) In line In[18], and for each m, I take the Max of possibly more than one solutions of In[16]. (3) Between In[19] and In[21] there is a lot of code that I have omitted. It defines the functions that start with the Greek letter sigma. (4) The critical line is In[21] where a pure number is not produced for Y[m]. All I want to say there is: if Y>0, sigmaH = sigma1H; if not it equals sigma0. (5) The final output of the code should be the table in In[23]. Any help in resolving this issue will be greatly appreciated.

Attachments:

For Namjoshi.nb

Thank you very much for your help. What I would like to do is to define a function that will give me the numerical values of Y without the arrow. My try f does not work. The arrow is still there. Is there another way to define such a function?

Hi Jasvesta,

-> defines a Rule, not an approximation. You can extract the RHS from a list of rules e.g.

ClearAll[x, y, z];
rules = {x -> 1, y -> 2, z -> 3};
rules[[All, 2]]
(* {1, 2, 3} *)

If you want x, y, z to be set to the corresponding RHS then

Apply@Set /@ rules;
{x, y, z}
(* {1, 2, 3} *)

Or using your example

y[#] /. Y[#] & /@ Range@8

Is that what you are looking for?