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D.2.3.9 writelist
Procedure from library inout.lib (see inout_lib).
- Usage:
writelist(file,name,L); file,name strings (file-name, list-name), L a list.
- Create:
a file with name ‘file‘, write the content of the list L into it and call the list ‘name‘, keeping the list structure
- Return:
no return value
- Note:
The syntax of writelist uses and is similar to the syntax of the write command of Singular which does not manage lists properly. If (file,name) = ("listfile","L1"), writelist creates (resp. appends if listfile exists) a file with name listfile and stores there the list L under the name L1. The Singular command execute(read("listfile")); assigns the content of L (stored in listfile) to a list L1.
On a UNIX system, write(">file",...) overwrites an existing file ‘file‘ while write("file",...) and write(">>file",...) append.
Example:
LIB "inout.lib";
ring r;
ideal i=x,y,z;
list k="Hi",nameof(basering),i,37;
writelist("zumSpass","lustig",k);
read("zumSpass");
→ list lustig;
→ lustig[1]=
→ Hi;
→ lustig[2]=
→ r;
→ lustig[3]=
→ x,y,z;
→ lustig[4]=
→ 37;
→
list L=res(i,0); //resolution of the ideal i
writelist("res_list","res-name",L); "";
→
read("res_list");
→ list res-name;
→ res-name[1]=
→ z,y,x;
→ res-name[2]=
→ -y*gen(1)+z*gen(2),-x*gen(1)+z*gen(3),-x*gen(2)+y*gen(3);
→ res-name[3]=
→ x*gen(1)-y*gen(2)+z*gen(3);
→
// execute(read("res_list")); would create a list with name res-name,
// which is the resolution of i (the same content as L)
system("sh","/bin/rm res_list zumSpass");
→ 0
// Under UNIX, this removes the files 'res_list' and 'zumSpass'
// Type help system; to get more information about the shell escape
// If your operating system does not accept the shell escape, you
// must remove the just created files 'zumSpass' and 'res_list' directly
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