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Cannot convert expression to function

Posted 11 years ago
Please look at following picture. Why when I call f[0,0], values of variables x and y were not replaced by 0 and 0??? Still x, y in there
POSTED BY: Dang Thanh
6 Replies
Posted 11 years ago
Ok, thanks. I got it!
POSTED BY: Dang Thanh
Posted 11 years ago
Once created I cannot make this box go away
 In[1]:= Clear[a, b];
 nmax = 10;
 mmax = 15;
 pts = Flatten[Table[{i - mmax/2, j - mmax/2, N[i^2 + j^2 - 5*i*j]}, {i, mmax}, {j, mmax}], 1];
 f1 = Sum[a[i]*x^i, {i, nmax}];
 f2 = Sum[b[i]*y^i, {i, nmax}];
 fpp = Expand[f1*f2];
 f = Function[{x, y}, Evaluate[fpp]];
 EE = Expand[Sum[Sqrt[1/mmax^2*(f[pts[[i,1]], pts[[i,2]]] - pts[[i,3]])^2], {i, mmax*mmax}]];
v = Join[Table[a[i], {i, nmax}], Table[b[i], {i, nmax}]];
w = v /. NMinimize[EE, v][[2]];
MapThread[Set, {v, w}];

In[13]:= a[1]

Out[13]= -0.024081

In[14]:= b[10]

Out[14]= 0.042064
POSTED BY: Bill Simpson
Posted 11 years ago
Thanks so much all. But I have other question, in following picture, I want to transfer value from result for parameters a and b. I know that I can use ./, but how I can use for long elements of table.

Wanna a and b receive these values (yellow marked)
POSTED BY: Dang Thanh
Sorry for the double posting. I was seconds late...

M.
POSTED BY: Marco Thiel
Hi,

please try to provide the code rather than an image of it next time. You might want to try this code:
 nmax = 10;
 mmax = 10;
 k = 0;
 pts = List[];
 pt = List[];
 For[i = 1, j <= nmax, i++,
   For[j = 1, j <= mmax, j++,
    AppendTo[pt, i - nmax/2];
    AppendTo[pt, j - nmax/2];
   AppendTo[pt, N[i^2 + j^2 - 5*i*j]];
   k = k + 1;
   AppendTo[pts, pt];
   pt = List[];
   ]
  ];
f1 := Sum[Subscript[a, i]*x^i, {i, nmax}];
f2 := Sum[Subscript[b, i]*y^i, {i, nmax}];
fpp = Expand[f1*f2];
fout[x_, y_] := Evaluate[fpp]

If you then evaluate
fout[0,0]

that results in 0.

M.
POSTED BY: Marco Thiel
Try
f = Function[{x, y}, Evaluate[fpp]];
POSTED BY: Ilian Gachevski
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