public class GenericStatic<T> {
static String o = "";
String oo() {
return o += "o";
}
public static void main(String[] args) {
GenericStatic<Object> a = new GenericStatic<Object>();
GenericStatic<String> b = new GenericStatic<String>();
System.out.println(a.oo());
System.out.println(b.oo());
}
}$ javac GenericStatic.java> (m <- matrix(1:4, nrow=2))This can cause problems when we want to go ahead and continue using the result in matrix operations:
[,1] [,2]
[1,] 1 3
[2,] 2 4
> (v <- m[1, 1:2])
[1] 1 3
> (v <- m[1, 1:2, drop=FALSE])
[,1] [,2]
[1,] 1 3
> v %*% m %*% t(v)
[,1]
[1,] 52
(%i8) display2d: false$
(%i9) %e^t;
(%o9) %e^t
(%i10) display2d: true$
(%i11) %e^t
;
t
(%o11) %e
#!/usr/bin/env pythonHere's a little game to drill you on somewhat similar sounding pairs of English words. I'm sure much could be done to improve it. Is the use of a class here kosher with Python practice? What's contrary to idiom here?
import os
import random
def say(word):
os.system("say " + word)
class Score:
def __init__(self):
self.total = 0
self.correct = 0
if __name__ == '__main__':
pairs = [["bed", "bad"], ["sped", "speed"],
["wary", "very"], ["bull", "ball"],
["mall", "mole"], ["pale", "pull"],
["soup", "stoop"], ["file", "fill"]]
scores = {}
for pair in pairs:
scores["".join(pair)] = Score()
input = ""
print("To quit, enter q")
while input != "q":
pair = random.choice(pairs)
word = random.choice(pair)
print("1) " + pair[0])
print("2) " + pair[1])
say(word)
input = raw_input("What did the computer say?: ")
input = input.strip()
if input != "q":
key = "".join(pair)
score = scores[key]
score.total += 1
if input == word:
score.correct += 1
print("Correct!")
else:
print("Wrong!")
print("You\'ve gotten the right answer for "
+ " vs ".join(pair) + " "
+ str(score.correct) + " out of "
+ str(score.total) + " times")
$ cat neg_dbl_max.c(This is running under Mac OS X 10.4 on an Intel Mac.) It'd be cool if gcc would recognize this constant and print it instead.
#include <float.h>
#include <stdio.h>
int main()
{
printf("%.50g\n", -DBL_MAX);
return 0;
}
$ gcc -Wall neg_dbl_max.c
$ ./a.out
-1.7976931348623157081452742373170435679807056752584e+308
(%i1) e : a^2 + b^2 + c^2;
2 2 2
(%o1) c + b + a
(%i2) ratsubst(r^2, a^2 + b^2 + c^2, e);
2
(%o2) r
(%i3) e : - 3 * a^2 - 3 * b^2 - 3 * c^2;
2 2 2
(%o3) - 3 c - 3 b - 3 a
(%i4) ratsubst(r^2, a^2 + b^2 + c^2, e);
2
(%o4) - 3 r
nan.c:$ gcc nan.c
#include <stdio.h>
#include <stdlib.h>
int main()
{
double x = strtod("NAN", 0);
printf("%f\n", x);
printf("%d\n", (int)(x == x));
return 0;
}
nan1.c:$ gcc nan1.c
#include <math.h>
#include <stdio.h>
int main()
{
printf("%f\n", NAN);
return 0;
}
vincent% cat nan2.c(I'm also working here under Linux. I'm not really sure what string I should drop in for the argument for nan. "hi!" also gives the same results as above. I'll stick with strtod for now.)
#include <math.h>
#include <stdio.h>
int main()
{
double x = nan("");
printf("%f\n", x);
printf("%d\n", (int)(x == x));
return 0;
}
vincent% gcc nan2.c -lm
vincent% ./a.out
0.000000
1
/**Earlier I had implemented this using only the second loop, now only used conditionally, with difference that I first rounded remaining * proportions[i] before truncating it to an int. However, this caused problems with too many points getting allocated, leading to a negative remainder and counts[0] getting an invalid value. Switching to simply truncating to zero, however, led us to sometimes not get exact results even when they were available. Eg, since (int) (97 * 0.5) = 48, the code under the if statement above divides 100 into (26, 49, 25) given proportions (0.25, 0.5, 0.25) rather (25, 50, 25) as one would hope. Hence, I have added the first loop and delegated the "safer" code to be called only in case of emergencies.
* On exit,
* counts[k] = number of points assigned to kth class,
* k = 0:(numClasses - 1) out of numPoints. Ensures that counts[k] > 0
* for every k while also sum(counts) = numPoints.
*/
void proportionsToCounts(const double* proportions,
int numClasses,
int numPoints,
int* counts)
{
int total = 0;
int numEmpty = 0;
int i;
assert(numPoints >= numClasses);
for (i = 0; i < numClasses; ++i) {
counts[i] = (int) round(numPoints * proportions[i]);
total += counts[i];
if (!counts[i]) {
++numEmpty;
}
}
if (numEmpty > 0 || total != numPoints) {
const double remaining = numPoints - numClasses;
int assigned = 0;
for (i = 1; i < numClasses; ++i) {
const int extra = (int) (remaining * proportions[i]);
assigned += extra;
counts[i] = 1 + extra;
}
counts[0] = 1 + numPoints - numClasses - assigned;
}
}
