for my problem Matlab crashes in the 5th loop of the main loop in worhp.cpp in the subroutine
if (GetUserAction(&cnt, callWorhp))
{
Worhp(&opt, &wsp, &par, &cnt);
// No DoneUserAction!
}
with a seg fault. It would be great if you could help me to debug by providing information on the opt, wsp, par and cnt structs and what to look for.
Thanks and best regards
I am currently having trouble with a similar issue. In one case, I was able to find an error by checking, whether the solver was able to terminate without an error when using approximated hessian matrices, instead of providing them myself. The error in this case occured, because I gave the library the wrong number of nonzero hessian entries and accessed entries of the hessian matrix that weren't allocated by the solver in my hessian function. Maybe your error is caused by a similar problem.
Kind regards,
Jan
Related
I am attempting to solve a non-convex quadratic optimization problem using Gurobi, but I have encountered an issue. Specifically, I have a specific objective function; however, I am only interested in finding a feasible solution. To do this, I tried two ways:
1- set my specific objective function as the model objective and set the parameter "SolutionLimit" to 1. This works fine, and Gurobi gives me a feasible solution.
2- give Gurobi no objective function (or set the objective to some arbitrary number like 0). In this case, Gurobi returns no feasible solution. The log it prints says:
Optimal solution found (tolerance 1.00e-04)
Warning: max constraint violation (1.5757e+01) exceeds tolerance
(model may be infeasible or unbounded - try turning presolve off)
Best objective -0.000000000000e+00, best bound -0.000000000000e+00, gap 0.0000%
I checked the solution it returned, and it is infeasible. I want the second method to work too. I have attempted to modify the solver parameters (such as "m.ModelSense = GRB.MAXIMIZE," "m.params.MIPFocus = 3," "m.params.NoRelHeurTime = 200," "m.params.DualReductions = 0," "m.params.Presolve = 2," and "m.params.Crossover = 0") in an effort to resolve this issue but have been unsuccessful. Are there any other parameters that I can adjust in order to successfully solve this problem?
This model has numerical issues; to understand more, please see Guidelines for Numerical Issues in the Gurobi Reference Manual.
I have a SCIP project to solve a binary problem with nonlinear objective function that works well but for some instances I got a message saying "the best solution is not feasible", and there is some violation in the constraints. (The violation is mostly very small)
To solve this issue, I added the SCIP_CALL_EXC( SCIPsetRealParam(scip, "numerics/feastol", 1e-5) to change the default value of feastol. But I get segmentation fault!
Following your helpful suggestion, the violation value is now much lower. My objective function is in the form of Min: AX+ LSqrt(BX). In the previous version, I had used an auxiliary variable, let say, Q such that Q^2 - L^2(BX) >=0 and the objective function was expressed as Min: AX+ Q . In the new version, I changed the inequality sign into equality and in combination with SCIPsetRealParam(scip, "numerics/feastol",1e-8), the violation in the constraints are much lower. What can I do more to decrease the violation value? Moreover, when I printed the value of feastol, I seenumerics/lpfeastol=1e-8 but lpfeastol is different from feastol!. So, why lpfeastol is modified instead?. I see the modified value of lpfeastol several times printed on screen when SCIP is solving the problem. I appreciate your help in advance
Maybe try changing the define of UPGSCALE in src/scip/cons_soc.c to some larger value.
The output for the lpfeastol is unfortunate, but normal. Reducing feastol automatically leads to adjusting lpfeastol, too. I cannot reproduce "I printed the value of feastol, I seenumerics/lpfeastol=1e-8 but lpfeastol is different from feastol".
I'm having trouble getting my .hdl files to loads in the HardwareSimulator. So far I have implemented FullAdder.hdl and Add16.hdl.
The error message I'm recieving is
line 22, zab has no source pin
Here is the relevant code for the Add16:
CHIP Add16 {
IN x[16], y[16];
OUT out[16];
PARTS:
HalfAdder(x=x[0],y=y[0],sum=out[0],carry=c);
FullAdder(x=x[1],y=y[1],c=c,sum=out[1],carry=d);
FullAdder(x=x[2],y=y[2],c=d,sum=out[2],carry=e);
FullAdder(x=x[3],y=y[3],c=e,sum=out[3],carry=f);
FullAdder(x=x[4],y=y[4],c=f,sum=out[4],carry=g);
FullAdder(x=x[5],y=y[5],c=g,sum=out[5],carry=h);
FullAdder(x=x[6],y=y[6],c=h,sum=out[6],carry=i);
FullAdder(x=x[7],y=y[7],c=i,sum=out[7],carry=j);
FullAdder(x=x[8],y=y[8],c=j,sum=out[8],carry=k);
FullAdder(x=x[9],y=y[9],c=k,sum=out[9],carry=l);
FullAdder(x=x[10],y=y[10],c=l,sum=out[10],carry=m);
FullAdder(x=x[11],y=y[11],c=m,sum=out[11],carry=n);
FullAdder(x=x[12],y=y[12],c=n,sum=out[12],carry=o);
FullAdder(x=x[13],y=y[13],c=o,sum=out[13],carry=p);
FullAdder(x=x[14],y=y[14],c=p,sum=out[14],carry=q);
FullAdder(x=x[15],y=y[15],c=q,sum=out[15],carry=drop);
}
I'm strugginling to find the error since I'm pretty sure I've implemented this chip in exactly the same way in the past and it worked fine.
As for the full adder, it's the same error message but for line 16.
I'll provide the relevant code for this part also:
CHIP FullAdder {
IN x, y, z; // 1-bit inputs
OUT sum, // Right bit of x + y + z
carry; // Left bit of x + y + z
PARTS:
HalfAdder(x=x,y=y,sum=xy,carry=zxy);
HalfAdder(x=z,y=xy,sum=sum,carry=s);
Or(x=zab,y=s,out=carry);
}
I can't wrap my mind around the error referring to line 16. That's way after the terminating bracket in FullAdder.
I've browsed the internet and as far as I can tell my implementation is perfectly correct. Any advice from anyone who are proficient in the Computer Processors area? This would definitely be useful for anyone else who are running into the same/similar problems.
Thanks
edit: According to this link Logic Gates my implementation looks more or less exactly the same. Could it be a faulty HardwareSim at my end? Although I doubt that since I've used it in the past and it was recommended to me by my University.
The problem is in the x input to your Or gate in the FullAdder. You are referring to a signal (pin) "zab" but no such signal is defined.
In future, please remember to post the entire files. It is hard to help you diagnose an error in line 16 when it is difficult to tell what line that actually is.
I am trying to use the G_LLL_XD function on the NTL library. Whenever I use the function in this format:
G_LLL_XD(B, delta); ,
the program works.
Though, when I want to change the default deep or prune variables and write the function in one of these ways:
G_LLL_XD(B, delta, deep, check, verbose);
G_LLL_XD(B, delta, prune, check, verbose);
during runtime, I get this error:
R610
- abort() has been called
and in the command prompt it says:
"sorry...deep insertions not implemented"
I find this very weird since whenever I use prune as a variable, I get this crash error, which I shouldn't because the function shouldn't be looking for deep insertion but prune, and when I do use deep as a variable and have implemented deep, I still get an error.
Can anybody help me understand what the problem is or how I can fix this? Thank you very much.
I dont found a argument prune for LLL function in NTL. But there is one for BKZ. Since the are both accept positive intergers, its only a naming confusion.
From the documentation:
NOTE: use of "deep" is obsolete, and has been "deprecated". It is
recommended to use BKZ_FP to achieve higher-quality reductions.
Moreover, the Givens versions do not support "deep", and setting
deep != 0 will raise an error in this case.
So you can not use G_LLL_XD with deep != 0 but LLL_XD should work (but it is deprecated).
But as mentioned, you should consider using BKZ_XD instead of LLL_XD.
A BKZ basis of a lattice is also LLL reduced, so there should be no problem. BKZ is slower than LLL but you can choose a small Blocksize, maybe 10 or 20 but also 2 or 4 will work, to speed the reduction up.
Since many of the Project Euler problems require you to do a divisibility check for quite a number of times, I've been trying to figure out the fastest way to perform this task in ZX81 BASIC.
So far I've compared (N/D) to INT(N/D) to check, whether N is dividable by D or not.
I have been thinking about doing the test in Z80 machine code, I haven't yet figured out how to use the variables in the BASIC in the machine code.
How can it be achieved?
You can do this very fast in machine code by subtracting repeatedly. Basically you have a procedure like:
set accumulator to N
subtract D
if carry flag is set then it is not divisible
if zero flag is set then it is divisible
otherwise repeat subtraction until one of the above occurs
The 8 bit version would be something like:
DIVISIBLE_TEST:
LD B,10
LD A,100
DIVISIBLE_TEST_LOOP:
SUB B
JR C, $END_DIVISIBLE_TEST
JR Z, $END_DIVISIBLE_TEST
JR $DIVISIBLE_TEST_LOOP
END_DIVISIBLE_TEST:
LD B,A
LD C,0
RET
Now, you can call from basic using USR. What USR returns is whatever's in the BC register pair, so you would probably want to do something like:
REM poke the memory addresses with the operands to load the registers
POKE X+1, D
POKE X+3, N
LET r = USR X
IF r = 0 THEN GOTO isdivisible
IF r <> 0 THEN GOTO isnotdivisible
This is an introduction I wrote to Z80 which should help you figure this out. This will explain the flags if you're not familiar with them.
There's a load more links to good Z80 stuff from the main site although it is Spectrum rather than ZX81 focused.
A 16 bit version would be quite similar but using register pair operations. If you need to go beyond 16 bits it would get a bit more convoluted.
How you load this is up to you - but the traditional method is using DATA statements and POKEs. You may prefer to have an assembler figure out the machine code for you though!
Your existing solution may be good enough. Only replace it with something faster if you find it to be a bottleneck in profiling.
(Said with a straight face, of course.)
And anyway, on the ZX81 you can just switch to FAST mode.
Don't know if RANDOMIZE USR is available in ZX81 but I think it can be used to call routines in assembly. To pass arguments you might need to use POKE to set some fixed memory locations before executing RANDOMIZE USR.
I remember to find a list of routines implemented in the ROM to support the ZX Basic. I'm sure there are a few to perform floating operation.
An alternative to floating point is to use fixed point math. It's a lot faster in these kind of situations where there is no math coprocessor.
You also might find more information in Sinclair User issues. They published some articles related to programming in the ZX Spectrum
You should place the values in some pre-known memory locations, first. Then use the same locations from within Z80 assembler. There is no parameter passing between the two.
This is based on what I (still) remember of ZX Spectrum 48. Good luck, but you might consider upgrading your hw. ;/
The problem with Z80 machine code is that it has no floating point ops (and no integer divide or multiply, for that matter). Implementing your own FP library in Z80 assembler is not trivial. Of course, you can use the built-in BASIC routines, but then you may as well just stick with BASIC.