Error in gp/code

["Swati, NoFirstName" <S10@email.sc.edu>]

Hello,

I am trying to compute the coefficients of \Delta^{a} \mid T_{p} modulo an integer m, store them as a column vector, and return the same (Values of a and p are quite large). I tried writing the code for it but getting an error. 

// parfor: mt: attempt to change the value of the exported variable B.) 

I am not sure how to fix this. Could someone help in this regard?

Here is my code:

comp(a,p, m) = { 

mf = mfpow(mfDelta(), a); 

mf1 = mfinit(mf); 

B = Col(0,a); 

H = mfhecke(mf1, mf, p); 

export(B, H); 

parfor(i = 1, a, B[i] = mfcoef(H, i) % m); 

return(B);

} 

Thanks,

Swati