Mathematica Errors when plotting but not when evaluating

[member 428835]

Hi PF!

Attached is a screenshot of my code:

The issue I'm facing is not being able to plot at line 21. It's weird because when I evaluate $\alpha[1/4]$ on it's own line I instantly receive a 5X1 vector. When I evaluate the Table[$\phi$] statement also shown in line 21 on it's own line I receive instantly a 5X1 vector too. Then when I copy-paste these results and dot them into each other I instantly get a good answer. So why can I not do this on the same line?

On line 21, I've tried changing the $x$ variable in $\phi$ to a $z$ and plotting in $z$, but it takes so long to run this way. I've also tried evaluating $\alpha$ since this seems to be the issue, but again no luck.

Any help would be awesome!

 

[DrClaude]

I'm not sure, but it could be because it is trying to evaluate $\phi$ using a numerical value for $x$. Try and see if the following helps:

Plot[\[Alpha][1/4].Table[\[Phi][xx, k, 1/4], {k, 1, 1/1/4 + 1}] /.
  xx -> x, {x, 0, 1}]

 

[member 428835]

I'm not sure, but it could be because it is trying to evaluate $\phi$ using a numerical value for $x$. Try and see if the following helps:

Plot[\[Alpha][1/4].Table[\[Phi][xx, k, 1/4], {k, 1, 1/1/4 + 1}] /.
  xx -> x, {x, 0, 1}]

Yea I tried this but it takes a ridiculous amount of time. Much longer than if I compute manually and then take the dot product. I'm glad I tried this first though! Makes me think I am doing something right!

 

[DrClaude]

It's hard sometimes to know in which order Mathematica is doing things.