Segmentation Fault in Pari/GP from gp2c-run

extDnkc(n, k, c, fPath) = {

/* =======================================================================

This function looks in fPath for a file called D_n_k_TN.csv where n and k

are input integers. It then applies the Extension process described in

Borwein to generate a new set of basic binary polynomials.

Unlike extDnk this function only records ("keeps") extended polynomials

Whose norms differ from k by c. By Proposition 5, the only useful values

of c are 0, 1, 2.

Although the function produces no direct outputs it does create a file.

Inputs:

n = poly width

k = poly norm

c = change in norm (out norm = in norm + c)

fPath = full file path to data sets

Outputs: (none but does create/append files)

Author: EE Griffin II

Date: Feb 12, 2023

========================================================================== */

my(fIn,fOut,fName,pwrOf2,qIdx,phiQ,degQ,strL,strS,pIdx,pV,p2V,pNorm,phiP);

/***************

Try to open the input file located in fPath. If this doesn't work bail

out with an error message.

***************/

fName = strjoin([fPath,strprintf("D_%d_%d_TN.csv", n, k)]);

iferr(fIn=fileopen(fName,"r"), ERR,

warning(strprintf("Bad input file: %s",fName)); return,errname(ERR)=="e_FILE");

/***************

As shown in Proposition 5 an element of D_n_k can only extend to an element in

D_n+1_k, D_n+1_k+1, or D_n+1_k+2. So the input is checked and a file is opened

if input c is in {0,1,2}.

***************/

if((c==0)||(c==1)||(c==2),

fName = strjoin([fPath,strprintf("D_%d_%d_TD.csv", n+1, k+c)]);

iferr(fOut=fileopen(fName,"a"), ERR,

warning(strprintf("Bad output file: %s",fName));

fileclose(fIn);return, errname(ERR)=="e_FILE");

warning(fName);,

warning(strprintf("Third input, c = norm change, must be in {0,1,2}"));return;

);

/***************

Each extension of a binary polynomial corresponds to adding a power of 2 to the

integer index of that polynomial. Calculate an array of 2^n

***************/

pwrOf2 = vector(1001, m, 2^m);

/***************

Loop over the input file line-by-line. Each D_n_k is a .csv file with 3

integers per row. They are:

qIdx = the integer index of the polynomial (=p(2))

phiQ = upper bound of extension loop

qDeg = the degree of q

(Note that two associated values are inputs:

qWid = n = the polynomial width (= # of non-zero coefficients in q)

qNorm = k = the largest coeff in the square of q

)

We use filereadstr to read in a line and then split it into three parts.

***************/

while(strL = filereadstr(fIn),

strS = strsplit(strL,",");

qIdx = eval(strS[1]);

phiQ = eval(strS[2]);

degQ = eval(strS[3]);

/***************

Loop over the possible extensions of q, using phiQ per Borwein

***************/

for(MM = degQ+1, phiQ,

/***************

Calculate the index, coefficients and norm of p. By the definition of the index,

adding another monomial of higher degree to q is the same as adding a power of 2

to the index of q.

***************/

pIdx = qIdx + pwrOf2[MM];

pV = binary(pIdx);

p2V=Vec(Pol(pV)^2);

pNorm = vecmax(p2V);

/***************

Check to see if p is a basic binary polynomial. If so, write out the data for it

***************/

if(pNorm == k+c,

if(#select(x->x,p2V[-MM-1..-1]) == MM+1,

phiP = 2*#pV - 1 - iferr(vecmax(select(x->(x==0), p2V, 1)), ERR, 0,errname(ERR)=="e_DOMAIN");

filewrite(fOut, strprintf("%d,%d,%d",pIdx, phiP ,MM));

);

/***************

Close the output files

***************/

iferr(fileclose(fOut), ERR,

warning(strprintf("Could not close output file")),errname(ERR)=="e_FILE"

);

/***************

Close the input file

***************/

fileclose(fIn);

};