.NET Inside Out Part 13 — Bypassing license checks

Written on Nov, 16, 2019

This is the thirteenth part of the .NET Inside Out series. For your convenience you can find other parts in the table of contents in Part 1 – Virtual and non-virtual calls in C# Last time we saw how to modify library on…

.NET Inside Out Part 12 — Modifying managed library on an IL level

Written on Nov, 09, 2019

This is the twelfth part of the .NET Inside Out series. For your convenience you can find other parts in the table of contents in Part 1 – Virtual and non-virtual calls in C# Imagine that you have a managed library which doesn’t…

Concurrency Part 10 — Reentrant mutex

Written on Nov, 02, 2019

This is the tenth part of the Concurrency series. For your convenience you can find other parts in the table of contents in Part 1 – Mutex performance in .NET We have already seen how to implement custom mutex using memory mapped files…

Concurrency Part 9 — Semaphores with custom locks

Written on Oct, 26, 2019

This is the ninth part of the Concurrency series. For your convenience you can find other parts in the table of contents in Part 1 – Mutex performance in .NET Last time we implemented custom mutex based on memory mapped files. We can…

Concurrency Part 8 — Tracking mutex owner

Written on Oct, 19, 2019

This is the eighth part of the Concurrency series. For your convenience you can find other parts in the table of contents in Part 1 – Mutex performance in .NET We know how to use global mutexes to synchronize processes. However, there is…

Concurrency Part 7 — Semaphores trickery

Written on Oct, 12, 2019

This is the seventh part of the Concurrency series. For your convenience you can find other parts in the table of contents in Part 1 – Mutex performance in .NET Last time we examined an interesting behavior of Mutex when it is abandoned.…

Capturing all output in Powershell

Written on Oct, 05, 2019

Today very simple trick to capture whole output from Powershell. Let’s see those files: 1.ps1

echo "1_1 STD OUT"
write-host "1_2 HOST OUT"
write-error "1_3 STD ERR"

.\2.ps1

echo "1_1 STD OUT"

write-host "1_2 HOST OUT"

write-error "1_3 STD ERR"

.\2.ps1

2.ps1

echo "2_1 STD OUT"
write-host "2_2 HOST OUT"
write-error "2_3 STD ERR"

.\3.bat

echo "2_1 STD OUT"

write-host "2_2 HOST OUT"

write-error "2_3 STD ERR"

.\3.bat

3.bat

echo "3_1 STD OUT"
echo "3_2 STD ERR" 1>&2
echo "3_2 STD 3" 1>&3

cscript 4.vbs

echo "3_1 STD OUT"

echo "3_2 STD ERR" 1>&2

echo "3_2 STD 3" 1>&3

cscript 4.vbs

4.vbs

Wscript.Echo "4_1 STD OUT"
Set fso = CreateObject ("Scripting.FileSystemObject")
Set stdout = fso.GetStandardStream (1)
Set stderr = fso.GetStandardStream (2)
stdout.WriteLine "4_2 STD OUT"
stderr.WriteLine "4_3 STD ERR"

Set WshShell = CreateObject("WScript.Shell")
Set WshShellExec = WshShell.Exec("5.exe")
WScript.StdOut.Write WshShellExec.StdOut.ReadAll
WScript.StdErr.Write WshShellExec.StdErr.ReadAll

Wscript.Echo "4_1 STD OUT"

Set fso = CreateObject ("Scripting.FileSystemObject")

Set stdout = fso.GetStandardStream (1)

Set stderr = fso.GetStandardStream (2)

stdout.WriteLine "4_2 STD OUT"

stderr.WriteLine "4_3 STD ERR"

Set WshShell = CreateObject("WScript.Shell")

Set WshShellExec = WshShell.Exec("5.exe")

WScript.StdOut.Write WshShellExec.StdOut.ReadAll

WScript.StdErr.Write WshShellExec.StdErr.ReadAll

5.exe

#include <iostream>
#include <cstdlib>

int main()
{
    std::cout << "5_1 STD OUT" << "\n";
    std::cerr << "5_2 STD ERR" << "\n";

    system("6.exe");
}

#include <iostream>

#include <cstdlib>

int main()

{

std::cout << "5_1 STD OUT" << "\n";

std::cerr << "5_2 STD ERR" << "\n";

system("6.exe");

}

6.exe

#include <iostream>
#include <cstdlib>

int main()
{
    std::cout << "6_1 STD OUT" << "\n";
    std::cerr << "6_2 STD ERR" << "\n";
}

#include <iostream>

#include <cstdlib>

int main()

{

std::cout << "6_1 STD OUT" << "\n";

std::cerr << "6_2 STD ERR" << "\n";

}

Let’s now run this with powershell:

PS C:\Afish\Playground> .\1.ps1
1_1 STD OUT
1_2 HOST OUT
C:\Afish\Playground\1.ps1 : 1_3 STD ERR
At line:1 char:1
+ .\1.ps1
+ ~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Write-Error], WriteErrorException
    + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,1.ps1

2_1 STD OUT
2_2 HOST OUT
C:\Afish\Playground\2.ps1 : 2_3 STD ERR
At C:\Afish\Playground\1.ps1:5 char:1
+ .\2.ps1
+ ~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Write-Error], WriteErrorException
    + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,2.ps1


C:\Afish\Playground>echo "3_1 STD OUT"
"3_1 STD OUT"

C:\Afish\Playground>echo "3_2 STD ERR"  1>&2
"3_2 STD ERR"

C:\Afish\Playground>echo "3_2 STD 3"  1>&3
"3_2 STD 3"

C:\Afish\Playground>cscript 4.vbs
Microsoft (R) Windows Script Host Version 5.812
Copyright (C) Microsoft Corporation. All rights reserved.

4_1 STD OUT
4_2 STD OUT
4_3 STD ERR
5_1 STD OUT
6_1 STD OUT
5_2 STD ERR
6_2 STD ERR

PS C:\Afish\Playground> .\1.ps1

1_1 STD OUT

1_2 HOST OUT

C:\Afish\Playground\1.ps1 : 1_3 STD ERR

At line:1 char:1

+ .\1.ps1

+ ~~~~~~~

+ CategoryInfo : NotSpecified: (:) [Write-Error], WriteErrorException

+ FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,1.ps1

2_1 STD OUT

2_2 HOST OUT

C:\Afish\Playground\2.ps1 : 2_3 STD ERR

At C:\Afish\Playground\1.ps1:5 char:1

+ .\2.ps1

+ ~~~~~~~

+ CategoryInfo : NotSpecified: (:) [Write-Error], WriteErrorException

+ FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,2.ps1

C:\Afish\Playground>echo "3_1 STD OUT"

"3_1 STD OUT"

C:\Afish\Playground>echo "3_2 STD ERR" 1>&2

"3_2 STD ERR"

C:\Afish\Playground>echo "3_2 STD 3" 1>&3

"3_2 STD 3"

C:\Afish\Playground>cscript 4.vbs

Microsoft (R) Windows Script Host Version 5.812

4_1 STD OUT

4_2 STD OUT

4_3 STD ERR

5_1 STD OUT

6_1 STD OUT

5_2 STD ERR

6_2 STD ERR

Okay, we have all STD OUT and STD ERR streams.…

Caching result of any function in C++

Written on Sep, 28, 2019

Imagine that you are writing a top-down dynamic algorithm. You already represented your dependencies as recursive functions and now you need to figure out how to decrease the memory usage and calculate things in correct order. On the other hand, you can just…

.NET Inside Out Part 11 — Using structs for devirtualization

Written on Sep, 21, 2019

This is the eleventh part of the .NET Inside Out series. For your convenience you can find other parts in the table of contents in Part 1 – Virtual and non-virtual calls in C# Last time we saw how type markers can result…

Custom memory allocation in C# Part 13 — In-place serialization

Written on Sep, 14, 2019

This is the thirteenth part of the Custom memory allocation series. For your convenience you can find other parts in the table of contents in Part 1 — Allocating object on a stack Recently Jean-Bernard Pellerin showed nice tricks for binary serialization in…

ILP Part 56 – Factorization benchmarking

Written on Sep, 07, 2019

This is the fifty sixth part of the ILP series. For your convenience you can find other parts in the table of contents in Part 1 – Boolean algebra Today we are going to benchmark factorization. First, let’s start with the code:

var primes = new int [] { 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997, 1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063, 1069, 1087, 1091, 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151, 1153, 1163, 1171, 1181, 1187, 1193, 1201, 1213, 1217, 1223, 1229, 1231, 1237, 1249, 1259, 1277, 1279, 1283, 1289, 1291, 1297, 1301, 1303, 1307, 1319, 1321, 1327, 1361, 1367, 1373, 1381, 1399, 1409, 1423, 1427, 1429, 1433, 1439, 1447, 1451, 1453, 1459, 1471, 1481, 1483, 1487, 1489, 1493, 1499, 1511, 1523, 1531, 1543, 1549, 1553, 1559, 1567, 1571, 1579, 1583, 1597, 1601, 1607, 1609, 1613, 1619, 1621, 1627, 1637, 1657, 1663, 1667, 1669, 1693, 1697, 1699, 1709, 1721, 1723, 1733, 1741, 1747, 1753, 1759, 1777, 1783, 1787, 1789, 1801, 1811, 1823, 1831, 1847, 1861, 1867, 1871, 1873, 1877, 1879, 1889, 1901, 1907, 1913, 1931, 1933, 1949, 1951, 1973, 1979, 1987, 1993, 1997, 1999, 2003, 2011, 2017, 2027, 2029, 2039, 2053, 2063, 2069, 2081, 2083, 2087, 2089, 2099, 2111, 2113, 2129, 2131, 2137, 2141, 2143, 2153, 2161, 2179, 2203, 2207, 2213, 2221, 2237, 2239, 2243, 2251, 2267, 2269, 2273, 2281, 2287, 2293, 2297, 2309, 2311, 2333, 2339, 2341, 2347, 2351, 2357, 2371, 2377, 2381, 2383, 2389, 2393, 2399, 2411, 2417, 2423, 2437, 2441, 2447, 2459, 2467, 2473, 2477, 2503, 2521, 2531, 2539, 2543, 2549, 2551, 2557, 2579, 2591, 2593, 2609, 2617, 2621, 2633, 2647, 2657, 2659, 2663, 2671, 2677, 2683, 2687, 2689, 2693, 2699, 2707, 2711, 2713, 2719, 2729, 2731, 2741, 2749, 2753, 2767, 2777, 2789, 2791, 2797, 2801, 2803, 2819, 2833, 2837, 2843, 2851, 2857, 2861, 2879, 2887, 2897, 2903, 2909, 2917, 2927, 2939, 2953, 2957, 2963, 2969, 2971, 2999, 3001, 3011, 3019, 3023, 3037, 3041, 3049, 3061, 3067, 3079, 3083, 3089, 3109, 3119, 3121, 3137, 3163, 3167, 3169, 3181, 3187, 3191, 3203, 3209, 3217, 3221, 3229, 3251, 3253, 3257, 3259, 3271, 3299, 3301, 3307, 3313, 3319, 3323, 3329, 3331, 3343, 3347, 3359, 3361, 3371, 3373, 3389, 3391, 3407, 3413, 3433, 3449, 3457, 3461, 3463, 3467, 3469, 3491, 3499, 3511, 3517, 3527, 3529, 3533, 3539, 3541, 3547, 3557, 3559, 3571, 3581, 3583, 3593, 3607, 3613, 3617, 3623, 3631, 3637, 3643, 3659, 3671, 3673, 3677, 3691, 3697, 3701, 3709, 3719, 3727, 3733, 3739, 3761, 3767, 3769, 3779, 3793, 3797, 3803, 3821, 3823, 3833, 3847, 3851, 3853, 3863, 3877, 3881, 3889, 3907, 3911, 3917, 3919, 3923, 3929, 3931, 3943, 3947, 3967, 3989, 4001, 4003, 4007, 4013, 4019, 4021, 4027, 4049, 4051, 4057, 4073, 4079, 4091, 4093, 4099, 4111, 4127, 4129, 4133, 4139, 4153, 4157, 4159, 4177, 4201, 4211, 4217, 4219, 4229, 4231, 4241, 4243, 4253, 4259, 4261, 4271, 4273, 4283, 4289, 4297, 4327, 4337, 4339, 4349, 4357, 4363, 4373, 4391, 4397, 4409, 4421, 4423, 4441, 4447, 4451, 4457, 4463, 4481, 4483, 4493, 4507, 4513, 4517, 4519, 4523, 4547, 4549, 4561, 4567, 4583, 4591, 4597, 4603, 4621, 4637, 4639, 4643, 4649, 4651, 4657, 4663, 4673, 4679, 4691, 4703, 4721, 4723, 4729, 4733, 4751, 4759, 4783, 4787, 4789, 4793, 4799, 4801, 4813, 4817, 4831, 4861, 4871, 4877, 4889, 4903, 4909, 4919, 4931, 4933, 4937, 4943, 4951, 4957, 4967, 4969, 4973, 4987, 4993, 4999, 5003, 5009, 5011, 5021, 5023, 5039, 5051, 5059, 5077, 5081, 5087, 5099, 5101, 5107, 5113, 5119, 5147, 5153, 5167, 5171, 5179, 5189, 5197, 5209, 5227, 5231, 5233, 5237, 5261, 5273, 5279, 5281, 5297, 5303, 5309, 5323, 5333, 5347, 5351, 5381, 5387, 5393, 5399, 5407, 5413, 5417, 5419, 5431, 5437, 5441, 5443, 5449, 5471, 5477, 5479, 5483, 5501, 5503, 5507, 5519, 5521, 5527, 5531, 5557, 5563, 5569, 5573, 5581, 5591, 5623, 5639, 5641, 5647, 5651, 5653, 5657, 5659, 5669, 5683, 5689, 5693, 5701, 5711, 5717, 5737, 5741, 5743, 5749, 5779, 5783, 5791, 5801, 5807, 5813, 5821, 5827, 5839, 5843, 5849, 5851, 5857, 5861, 5867, 5869, 5879, 5881, 5897, 5903, 5923, 5927, 5939, 5953, 5981, 5987, 6007, 6011, 6029, 6037, 6043, 6047, 6053, 6067, 6073, 6079, 6089, 6091, 6101, 6113, 6121, 6131, 6133, 6143, 6151, 6163, 6173, 6197, 6199, 6203, 6211, 6217, 6221, 6229, 6247, 6257, 6263, 6269, 6271, 6277, 6287, 6299, 6301, 6311, 6317, 6323, 6329, 6337, 6343, 6353, 6359, 6361, 6367, 6373, 6379, 6389, 6397, 6421, 6427, 6449, 6451, 6469, 6473, 6481, 6491, 6521, 6529, 6547, 6551, 6553, 6563, 6569, 6571, 6577, 6581, 6599, 6607, 6619, 6637, 6653, 6659, 6661, 6673, 6679, 6689, 6691, 6701, 6703, 6709, 6719, 6733, 6737, 6761, 6763, 6779, 6781, 6791, 6793, 6803, 6823, 6827, 6829, 6833, 6841, 6857, 6863, 6869, 6871, 6883, 6899, 6907, 6911, 6917, 6947, 6949, 6959, 6961, 6967, 6971, 6977, 6983, 6991, 6997, 7001, 7013, 7019, 7027, 7039, 7043, 7057, 7069, 7079, 7103, 7109, 7121, 7127, 7129, 7151, 7159, 7177, 7187, 7193, 7207, 7211, 7213, 7219, 7229, 7237, 7243, 7247, 7253, 7283, 7297, 7307, 7309, 7321, 7331, 7333, 7349, 7351, 7369, 7393, 7411, 7417, 7433, 7451, 7457, 7459, 7477, 7481, 7487, 7489, 7499, 7507, 7517, 7523, 7529, 7537, 7541, 7547, 7549, 7559, 7561, 7573, 7577, 7583, 7589, 7591, 7603, 7607, 7621, 7639, 7643, 7649, 7669, 7673, 7681, 7687, 7691, 7699, 7703, 7717, 7723, 7727, 7741, 7753, 7757, 7759, 7789, 7793, 7817, 7823, 7829, 7841, 7853, 7867, 7873, 7877, 7879, 7883, 7901, 7907, 7919, 7927, 7933, 7937, 7949, 7951, 7963, 7993, 8009, 8011, 8017, 8039, 8053, 8059, 8069, 8081, 8087, 8089, 8093, 8101, 8111, 8117, 8123, 8147, 8161, 8167, 8171, 8179, 8191, 8209, 8219, 8221, 8231, 8233, 8237, 8243, 8263, 8269, 8273, 8287, 8291, 8293, 8297, 8311, 8317, 8329, 8353, 8363, 8369, 8377, 8387, 8389, 8419, 8423, 8429, 8431, 8443, 8447, 8461, 8467, 8501, 8513, 8521, 8527, 8537, 8539, 8543, 8563, 8573, 8581, 8597, 8599, 8609, 8623, 8627, 8629, 8641, 8647, 8663, 8669, 8677, 8681, 8689, 8693, 8699, 8707, 8713, 8719, 8731, 8737, 8741, 8747, 8753, 8761, 8779, 8783, 8803, 8807, 8819, 8821, 8831, 8837, 8839, 8849, 8861, 8863, 8867, 8887, 8893, 8923, 8929, 8933, 8941, 8951, 8963, 8969, 8971, 8999, 9001, 9007, 9011, 9013, 9029, 9041, 9043, 9049, 9059, 9067, 9091, 9103, 9109, 9127, 9133, 9137, 9151, 9157, 9161, 9173, 9181, 9187, 9199, 9203, 9209, 9221, 9227, 9239, 9241, 9257, 9277, 9281, 9283, 9293, 9311, 9319, 9323, 9337, 9341, 9343, 9349, 9371, 9377, 9391, 9397, 9403, 9413, 9419, 9421, 9431, 9433, 9437, 9439, 9461, 9463, 9467, 9473, 9479, 9491, 9497, 9511, 9521, 9533, 9539, 9547, 9551, 9587, 9601, 9613, 9619, 9623, 9629, 9631, 9643, 9649, 9661, 9677, 9679, 9689, 9697, 9719, 9721, 9733, 9739, 9743, 9749, 9767, 9769, 9781, 9787, 9791, 9803, 9811, 9817, 9829, 9833, 9839, 9851, 9857, 9859, 9871, 9883, 9887, 9901, 9907, 9923, 9929, 9931, 9941, 9949, 9967, 9973 };

var solverSizes = new int[] { 5, 10, 15 };

foreach(var size in solverSizes) {
	Console.WriteLine("Size " + size);
	foreach(var prime1 in primes) {
		foreach(var prime2 in primes) {
			if(prime2 < prime1) continue;

			var solver = new CplexMilpSolver(size);
			var multiplied = prime1 * prime2;
			if(multiplied >= solver.MaximumIntegerValue) break;

			var multipliedVar = solver.FromConstant(multiplied);
			var a = solver.CreateAnonymous(Domain.PositiveOrZeroInteger);
			var b = solver.CreateAnonymous(Domain.PositiveOrZeroInteger);

			solver.Set(ConstraintType.Equal, a.Operation(OperationType.Multiplication, b), solver.FromConstant(multiplied));
			solver.Set(ConstraintType.LessOrEqual, a, b);
			solver.Set(ConstraintType.GreaterOrEqual, a, solver.FromConstant(2));

			solver.AddGoal("g", solver.FromConstant(0));

			var stopwatch = new Stopwatch();
			stopwatch.Start();
			try {
				solver.Solve();
				stopwatch.Stop();

				var prime1Calculated = solver.GetValue(a);
				var prime2Calculated = solver.GetValue(b);

				Console.WriteLine("For " + prime1 + " " + prime2 + " obtained " + prime1Calculated + " " + prime2Calculated + " in " + stopwatch.Elapsed);
			}
			catch {
				Console.WriteLine("For " + prime1 + " " + prime2 + " obtained -1 -1 in 00:00:00.0000000");
			}
		}
		Console.WriteLine();
	}
}

var primes = new int [] { 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997, 1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063, 1069, 1087, 1091, 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151, 1153, 1163, 1171, 1181, 1187, 1193, 1201, 1213, 1217, 1223, 1229, 1231, 1237, 1249, 1259, 1277, 1279, 1283, 1289, 1291, 1297, 1301, 1303, 1307, 1319, 1321, 1327, 1361, 1367, 1373, 1381, 1399, 1409, 1423, 1427, 1429, 1433, 1439, 1447, 1451, 1453, 1459, 1471, 1481, 1483, 1487, 1489, 1493, 1499, 1511, 1523, 1531, 1543, 1549, 1553, 1559, 1567, 1571, 1579, 1583, 1597, 1601, 1607, 1609, 1613, 1619, 1621, 1627, 1637, 1657, 1663, 1667, 1669, 1693, 1697, 1699, 1709, 1721, 1723, 1733, 1741, 1747, 1753, 1759, 1777, 1783, 1787, 1789, 1801, 1811, 1823, 1831, 1847, 1861, 1867, 1871, 1873, 1877, 1879, 1889, 1901, 1907, 1913, 1931, 1933, 1949, 1951, 1973, 1979, 1987, 1993, 1997, 1999, 2003, 2011, 2017, 2027, 2029, 2039, 2053, 2063, 2069, 2081, 2083, 2087, 2089, 2099, 2111, 2113, 2129, 2131, 2137, 2141, 2143, 2153, 2161, 2179, 2203, 2207, 2213, 2221, 2237, 2239, 2243, 2251, 2267, 2269, 2273, 2281, 2287, 2293, 2297, 2309, 2311, 2333, 2339, 2341, 2347, 2351, 2357, 2371, 2377, 2381, 2383, 2389, 2393, 2399, 2411, 2417, 2423, 2437, 2441, 2447, 2459, 2467, 2473, 2477, 2503, 2521, 2531, 2539, 2543, 2549, 2551, 2557, 2579, 2591, 2593, 2609, 2617, 2621, 2633, 2647, 2657, 2659, 2663, 2671, 2677, 2683, 2687, 2689, 2693, 2699, 2707, 2711, 2713, 2719, 2729, 2731, 2741, 2749, 2753, 2767, 2777, 2789, 2791, 2797, 2801, 2803, 2819, 2833, 2837, 2843, 2851, 2857, 2861, 2879, 2887, 2897, 2903, 2909, 2917, 2927, 2939, 2953, 2957, 2963, 2969, 2971, 2999, 3001, 3011, 3019, 3023, 3037, 3041, 3049, 3061, 3067, 3079, 3083, 3089, 3109, 3119, 3121, 3137, 3163, 3167, 3169, 3181, 3187, 3191, 3203, 3209, 3217, 3221, 3229, 3251, 3253, 3257, 3259, 3271, 3299, 3301, 3307, 3313, 3319, 3323, 3329, 3331, 3343, 3347, 3359, 3361, 3371, 3373, 3389, 3391, 3407, 3413, 3433, 3449, 3457, 3461, 3463, 3467, 3469, 3491, 3499, 3511, 3517, 3527, 3529, 3533, 3539, 3541, 3547, 3557, 3559, 3571, 3581, 3583, 3593, 3607, 3613, 3617, 3623, 3631, 3637, 3643, 3659, 3671, 3673, 3677, 3691, 3697, 3701, 3709, 3719, 3727, 3733, 3739, 3761, 3767, 3769, 3779, 3793, 3797, 3803, 3821, 3823, 3833, 3847, 3851, 3853, 3863, 3877, 3881, 3889, 3907, 3911, 3917, 3919, 3923, 3929, 3931, 3943, 3947, 3967, 3989, 4001, 4003, 4007, 4013, 4019, 4021, 4027, 4049, 4051, 4057, 4073, 4079, 4091, 4093, 4099, 4111, 4127, 4129, 4133, 4139, 4153, 4157, 4159, 4177, 4201, 4211, 4217, 4219, 4229, 4231, 4241, 4243, 4253, 4259, 4261, 4271, 4273, 4283, 4289, 4297, 4327, 4337, 4339, 4349, 4357, 4363, 4373, 4391, 4397, 4409, 4421, 4423, 4441, 4447, 4451, 4457, 4463, 4481, 4483, 4493, 4507, 4513, 4517, 4519, 4523, 4547, 4549, 4561, 4567, 4583, 4591, 4597, 4603, 4621, 4637, 4639, 4643, 4649, 4651, 4657, 4663, 4673, 4679, 4691, 4703, 4721, 4723, 4729, 4733, 4751, 4759, 4783, 4787, 4789, 4793, 4799, 4801, 4813, 4817, 4831, 4861, 4871, 4877, 4889, 4903, 4909, 4919, 4931, 4933, 4937, 4943, 4951, 4957, 4967, 4969, 4973, 4987, 4993, 4999, 5003, 5009, 5011, 5021, 5023, 5039, 5051, 5059, 5077, 5081, 5087, 5099, 5101, 5107, 5113, 5119, 5147, 5153, 5167, 5171, 5179, 5189, 5197, 5209, 5227, 5231, 5233, 5237, 5261, 5273, 5279, 5281, 5297, 5303, 5309, 5323, 5333, 5347, 5351, 5381, 5387, 5393, 5399, 5407, 5413, 5417, 5419, 5431, 5437, 5441, 5443, 5449, 5471, 5477, 5479, 5483, 5501, 5503, 5507, 5519, 5521, 5527, 5531, 5557, 5563, 5569, 5573, 5581, 5591, 5623, 5639, 5641, 5647, 5651, 5653, 5657, 5659, 5669, 5683, 5689, 5693, 5701, 5711, 5717, 5737, 5741, 5743, 5749, 5779, 5783, 5791, 5801, 5807, 5813, 5821, 5827, 5839, 5843, 5849, 5851, 5857, 5861, 5867, 5869, 5879, 5881, 5897, 5903, 5923, 5927, 5939, 5953, 5981, 5987, 6007, 6011, 6029, 6037, 6043, 6047, 6053, 6067, 6073, 6079, 6089, 6091, 6101, 6113, 6121, 6131, 6133, 6143, 6151, 6163, 6173, 6197, 6199, 6203, 6211, 6217, 6221, 6229, 6247, 6257, 6263, 6269, 6271, 6277, 6287, 6299, 6301, 6311, 6317, 6323, 6329, 6337, 6343, 6353, 6359, 6361, 6367, 6373, 6379, 6389, 6397, 6421, 6427, 6449, 6451, 6469, 6473, 6481, 6491, 6521, 6529, 6547, 6551, 6553, 6563, 6569, 6571, 6577, 6581, 6599, 6607, 6619, 6637, 6653, 6659, 6661, 6673, 6679, 6689, 6691, 6701, 6703, 6709, 6719, 6733, 6737, 6761, 6763, 6779, 6781, 6791, 6793, 6803, 6823, 6827, 6829, 6833, 6841, 6857, 6863, 6869, 6871, 6883, 6899, 6907, 6911, 6917, 6947, 6949, 6959, 6961, 6967, 6971, 6977, 6983, 6991, 6997, 7001, 7013, 7019, 7027, 7039, 7043, 7057, 7069, 7079, 7103, 7109, 7121, 7127, 7129, 7151, 7159, 7177, 7187, 7193, 7207, 7211, 7213, 7219, 7229, 7237, 7243, 7247, 7253, 7283, 7297, 7307, 7309, 7321, 7331, 7333, 7349, 7351, 7369, 7393, 7411, 7417, 7433, 7451, 7457, 7459, 7477, 7481, 7487, 7489, 7499, 7507, 7517, 7523, 7529, 7537, 7541, 7547, 7549, 7559, 7561, 7573, 7577, 7583, 7589, 7591, 7603, 7607, 7621, 7639, 7643, 7649, 7669, 7673, 7681, 7687, 7691, 7699, 7703, 7717, 7723, 7727, 7741, 7753, 7757, 7759, 7789, 7793, 7817, 7823, 7829, 7841, 7853, 7867, 7873, 7877, 7879, 7883, 7901, 7907, 7919, 7927, 7933, 7937, 7949, 7951, 7963, 7993, 8009, 8011, 8017, 8039, 8053, 8059, 8069, 8081, 8087, 8089, 8093, 8101, 8111, 8117, 8123, 8147, 8161, 8167, 8171, 8179, 8191, 8209, 8219, 8221, 8231, 8233, 8237, 8243, 8263, 8269, 8273, 8287, 8291, 8293, 8297, 8311, 8317, 8329, 8353, 8363, 8369, 8377, 8387, 8389, 8419, 8423, 8429, 8431, 8443, 8447, 8461, 8467, 8501, 8513, 8521, 8527, 8537, 8539, 8543, 8563, 8573, 8581, 8597, 8599, 8609, 8623, 8627, 8629, 8641, 8647, 8663, 8669, 8677, 8681, 8689, 8693, 8699, 8707, 8713, 8719, 8731, 8737, 8741, 8747, 8753, 8761, 8779, 8783, 8803, 8807, 8819, 8821, 8831, 8837, 8839, 8849, 8861, 8863, 8867, 8887, 8893, 8923, 8929, 8933, 8941, 8951, 8963, 8969, 8971, 8999, 9001, 9007, 9011, 9013, 9029, 9041, 9043, 9049, 9059, 9067, 9091, 9103, 9109, 9127, 9133, 9137, 9151, 9157, 9161, 9173, 9181, 9187, 9199, 9203, 9209, 9221, 9227, 9239, 9241, 9257, 9277, 9281, 9283, 9293, 9311, 9319, 9323, 9337, 9341, 9343, 9349, 9371, 9377, 9391, 9397, 9403, 9413, 9419, 9421, 9431, 9433, 9437, 9439, 9461, 9463, 9467, 9473, 9479, 9491, 9497, 9511, 9521, 9533, 9539, 9547, 9551, 9587, 9601, 9613, 9619, 9623, 9629, 9631, 9643, 9649, 9661, 9677, 9679, 9689, 9697, 9719, 9721, 9733, 9739, 9743, 9749, 9767, 9769, 9781, 9787, 9791, 9803, 9811, 9817, 9829, 9833, 9839, 9851, 9857, 9859, 9871, 9883, 9887, 9901, 9907, 9923, 9929, 9931, 9941, 9949, 9967, 9973 };

var solverSizes = new int[] { 5, 10, 15 };

foreach(var size in solverSizes) {

Console.WriteLine("Size " + size);

foreach(var prime1 in primes) {

foreach(var prime2 in primes) {

if(prime2 < prime1) continue;

var solver = new CplexMilpSolver(size);

var multiplied = prime1 * prime2;

if(multiplied >= solver.MaximumIntegerValue) break;

var multipliedVar = solver.FromConstant(multiplied);

var a = solver.CreateAnonymous(Domain.PositiveOrZeroInteger);

var b = solver.CreateAnonymous(Domain.PositiveOrZeroInteger);

solver.Set(ConstraintType.Equal, a.Operation(OperationType.Multiplication, b), solver.FromConstant(multiplied));

solver.Set(ConstraintType.LessOrEqual, a, b);

solver.Set(ConstraintType.GreaterOrEqual, a, solver.FromConstant(2));

solver.AddGoal("g", solver.FromConstant(0));

var stopwatch = new Stopwatch();

stopwatch.Start();

try {

solver.Solve();

stopwatch.Stop();

var prime1Calculated = solver.GetValue(a);

var prime2Calculated = solver.GetValue(b);

Console.WriteLine("For " + prime1 + " " + prime2 + " obtained " + prime1Calculated + " " + prime2Calculated + " in " + stopwatch.Elapsed);

}

catch {

Console.WriteLine("For " + prime1 + " " + prime2 + " obtained -1 -1 in 00:00:00.0000000");

}

Console.WriteLine();

}

…

.NET Inside Out Part 10 — Using type markers for low level optimizations

Written on Aug, 31, 2019

This is the tenth part of the .NET Inside Out series. For your convenience you can find other parts in the table of contents in Part 1 – Virtual and non-virtual calls in C# If you are interested in the topic see the…

Decreasing pain of stolen focus

Written on Aug, 24, 2019

One of the most irritating thing in Windows is no way to prevent an application from stealing focus. There are multiple questions on Stack Overflow regarding the issue, there are rumors that Microsoft wanted to do something but they cannot detect it reliably.…

Comparing numbers is hard

Written on Aug, 17, 2019

We know that to compare floating point values we should use epsilon and not just compare bits. We may run into similar issues when comparing BigDecimal in Java:

BigDecimal a = BigDecimal.valueOf(0);
BigDecimal b = BigDecimal.valueOf(Double.valueOf(0));
System.out.println(a.equals(b));

BigDecimal a = BigDecimal.valueOf(0);

BigDecimal b = BigDecimal.valueOf(Double.valueOf(0));

System.out.println(a.equals(b));

What is the output? Of course it is false, otherwise I wouldn’t write this…

Custom memory allocation in C# Part 12 — Hiding objects from GC

Written on Aug, 10, 2019

This is the twelfth part of the Custom memory allocation series. For your convenience you can find other parts in the table of contents in Part 1 — Allocating object on a stack We already know how to allocate memory anywhere on the…

Modifying Android application on a binary level

Written on Aug, 03, 2019

Recently I had to modify an existing Android application for which I didn’t have a source code, only APK file. This may sound like an impossible task but actually it is pretty easy (very tedious, though). I didn’t want to use any compilers…

Machine Learning Part 8 — Backpropagation in neural net in SQL

Written on Jul, 27, 2019

This is the eighth part of the ML series. For your convenience you can find other parts in the table of contents in Part 1 – Linear regression in MXNet Last time we saw forward propagation in neural net. Today we are going…

Machine Learning Part 7 — Forward propagation in neural net in SQL

Written on Jul, 20, 2019

This is the seventh part of the ML series. For your convenience you can find other parts in the table of contents in Part 1 – Linear regression in MXNet Today we are going to create a neural net and calculate forward propagation…

Windowing functions in recursive CTE

Written on Jul, 13, 2019

Today we will see an interesting case of incompatibility between MS SQL Server 2017 and PostgreSQL 9.6 (and different versions as well). Let’s start with this code:

WITH dummy AS(
    SELECT 1 AS rowValue, 0 AS phase
    UNION ALL
    SELECT 2 AS rowValue, 0 AS phase
),
solution AS (
    SELECT * FROM dummy
),
solution2 AS(
    SELECT
        SUM(rowValue) OVER (PARTITION BY phase) AS rowValue,
        phase + 1 AS phase
    FROM solution
    WHERE phase = 0
)
SELECT *
FROM solution2
WHERE phase = 1

WITH dummy AS(

SELECT 1 AS rowValue, 0 AS phase

UNION ALL

SELECT 2 AS rowValue, 0 AS phase

solution AS (

SELECT * FROM dummy

solution2 AS(

SELECT

SUM(rowValue) OVER (PARTITION BY phase) AS rowValue,

phase + 1 AS phase

FROM solution

WHERE phase = 0

)

SELECT *

FROM solution2

WHERE phase = 1

We emulate a recursive CTE. We have two columns in source dataset, we want to…

Running On Screen Keyboard in Windows 10 in C#

Written on Jul, 06, 2019

Today something supposedly very simple. How to run On Screen Keyboard from C#? Easy enough you say and type the following code:

Process.Start(@"osk.exe");

1	Process.Start(@"osk.exe");

And then you compile it as Any CPU, run on Windows 10 x64 and you get the following error: What…