Hi all,

I think the developers should pay attention to this problem.

This simple expression with Threads:-Map executed perfectly on my machine with 8-threaded CPU and 16 GB RAM:

Threads:-Map(proc (i) options operator, arrow; ln(i)/2. end proc, [`$`(1 .. 10^7)]);

But the similar expression with Grid:-Map never be executed:

Grid:-Map(proc (i) options operator, arrow; ln(i)/2. end proc, [`$`(1 .. 10^7)]);

Maple or freezed, or crashed every time. Although the consuming of memory is not reached even 50%.

The similar problem exist for Grid:-Seq too. With `$`(1 .. 3*10^6) Grid:-Map and Grid:-Seq executed normally. With `$`(1 .. 5*10^6) - 50/50. But not with `$`(1 .. 10^7).

Is this a real bug of Grid:-Map and Grid:-Seq ?

Or is exist a way to fix this problem?

Thanks.

Updated:

I got a new error behavior of Grid:-Map in this case instead crash or freeze:

Grid:-Launch(numnodes = 8);

st := time[real](); Grid:-Map(proc (i) options operator, arrow; ln(i)/2. end proc, [`$`(1 .. 10^7)]);

time[real]()-st;

print(`output redirected...`); # input placeholder

`System error, `, "bad id"
2267.482

I hope this helps developers to fix this bug.

What is the correct mode of using dsolve/numeric/compile with Grid package?

I've tried a lot of different, but only one turned out to be working is by using Grid:-Seq(dsolve..., i=1).

For example:

...

dsol := Grid:-Seq(dsolve(dsys, numeric, parameters = [bb, qq, prf0, `pθf0`], compile = true, optimize = true, output = listprocedure, maxfun = 0), i = 1):

dsol3 := proc (tt) try dsol[3](tt) catch "cannot evaluate the solution further": tt = 0. end try end proc:

st := time[real]():

A := Array([Grid:-Seq([seq(op(2, [dsol[1](parameters = [b[i, j], q[i, j], pr[i, j], `pθ`[i, j]]), rhs(dsol3(-10^6))]), j = 1 .. sz[2])], i = 1 .. sz[1])]);

time[real]()-st;

example.mw

But this mode not stable and causing to this error very often:

Error, (in dsolve/numeric/SC/preproc) unable to post-link (rc=31), please try again, and if that fails check that your Windows SDK installation is up to date, and compatible with your Windows compiler

How I can fix this problem?