int numeric::compare_same_type(basic const & other) const
{
- ASSERT(is_exactly_of_type(other, numeric));
+ GINAC_ASSERT(is_exactly_of_type(other, numeric));
numeric const & o = static_cast<numeric &>(const_cast<basic &>(other));
if (*value == *o.value) {
bool numeric::is_equal_same_type(basic const & other) const
{
- ASSERT(is_exactly_of_type(other,numeric));
+ GINAC_ASSERT(is_exactly_of_type(other,numeric));
numeric const *o = static_cast<numeric const *>(&other);
return is_equal(*o);
* if the number is really an integer before calling this method. */
int numeric::to_int(void) const
{
- ASSERT(is_integer());
+ GINAC_ASSERT(is_integer());
return cl_I_to_int(The(cl_I)(*value));
}
* if the number is really not complex before calling this method. */
double numeric::to_double(void) const
{
- ASSERT(is_real());
+ GINAC_ASSERT(is_real());
return cl_double_approx(realpart(*value));
}
/** Numerator. Computes the numerator of rational numbers, rationalized
* numerator of complex if real and imaginary part are both rational numbers
- * (i.e numer(4/3+5/6*I) == 8+5*I), the number itself in all other cases. */
+ * (i.e numer(4/3+5/6*I) == 8+5*I), the number carrying the sign in all other
+ * cases. */
numeric numeric::numer(void) const
{
if (is_integer()) {
return ::atanh(*x.value); // -> CLN
}
+/** Numeric evaluation of Riemann's Zeta function. Currently works only for
+ * integer arguments. */
+numeric zeta(numeric const & x)
+{
+ if (x.is_integer())
+ return ::cl_zeta(x.to_int()); // -> CLN
+ else
+ clog << "zeta(): Does anybody know good way to calculate this numerically?" << endl;
+ return numeric(0);
+}
+
/** The gamma function.
- * stub stub stub stub stub stub! */
+ * This is only a stub! */
numeric gamma(numeric const & x)
{
- clog << "gamma(): Nobody expects the Spanish inquisition" << endl;
+ clog << "gamma(): Does anybody know good way to calculate this numerically?" << endl;
+ return numeric(0);
+}
+
+/** The psi function (aka polygamma function).
+ * This is only a stub! */
+numeric psi(numeric const & x)
+{
+ clog << "psi(): Does anybody know good way to calculate this numerically?" << endl;
+ return numeric(0);
+}
+
+/** The psi functions (aka polygamma functions).
+ * This is only a stub! */
+numeric psi(numeric const & n, numeric const & x)
+{
+ clog << "psi(): Does anybody know good way to calculate this numerically?" << endl;
return numeric(0);
}
{
// META-NOTE: The whole shit here will become obsolete and may be moved
// out once CLN learns about double factorial, which should be as soon as
- // 1.0.3 rolls out.
+ // 1.0.3 rolls out!
// We store the results separately for even and odd arguments. This has
// the advantage that we don't have to compute any even result at all if
static vector<numeric> oddresults;
static int highest_oddresult = -1;
- if ( nn == numeric(-1) ) {
+ if (nn == numeric(-1)) {
return numONE();
}
- if ( !nn.is_nonneg_integer() ) {
+ if (!nn.is_nonneg_integer()) {
throw (std::range_error("numeric::doublefactorial(): argument must be integer >= -1"));
}
- if ( nn.is_even() ) {
+ if (nn.is_even()) {
int n = nn.div(numTWO()).to_int();
- if ( n <= highest_evenresult ) {
+ if (n <= highest_evenresult) {
return evenresults[n];
}
- if ( evenresults.capacity() < (unsigned)(n+1) ) {
+ if (evenresults.capacity() < (unsigned)(n+1)) {
evenresults.reserve(n+1);
}
- if ( highest_evenresult < 0 ) {
+ if (highest_evenresult < 0) {
evenresults.push_back(numONE());
highest_evenresult=0;
}
return evenresults[n];
} else {
int n = nn.sub(numONE()).div(numTWO()).to_int();
- if ( n <= highest_oddresult ) {
+ if (n <= highest_oddresult) {
return oddresults[n];
}
- if ( oddresults.capacity() < (unsigned)n ) {
+ if (oddresults.capacity() < (unsigned)n) {
oddresults.reserve(n+1);
}
- if ( highest_oddresult < 0 ) {
+ if (highest_oddresult < 0) {
oddresults.push_back(numONE());
highest_oddresult=0;
}
}
}
-/** The Binomial function. It computes the binomial coefficients. If the
- * arguments are both nonnegative integers and 0 <= k <= n, then
- * binomial(n, k) = n!/k!/(n-k)! which is the number of ways of choosing k
- * objects from n distinct objects. If k > n, then binomial(n,k) returns 0. */
+/** The Binomial coefficients. It computes the binomial coefficients. For
+ * integer n and k and positive n this is the number of ways of choosing k
+ * objects from n distinct objects. If n is negative, the formula
+ * binomial(n,k) == (-1)^k*binomial(k-n-1,k) is used to compute the result. */
numeric binomial(numeric const & n, numeric const & k)
{
- if (n.is_nonneg_integer() && k.is_nonneg_integer()) {
- return numeric(::binomial(n.to_int(),k.to_int())); // -> CLN
- } else {
- // should really be gamma(n+1)/(gamma(r+1)/gamma(n-r+1)
- return numeric(0);
+ if (n.is_integer() && k.is_integer()) {
+ if (n.is_nonneg_integer()) {
+ if (k.compare(n)!=1 && k.compare(numZERO())!=-1)
+ return numeric(::binomial(n.to_int(),k.to_int())); // -> CLN
+ else
+ return numZERO();
+ } else {
+ return numMINUSONE().power(k)*binomial(k-n-numONE(),k);
+ }
+ }
+
+ // should really be gamma(n+1)/(gamma(r+1)/gamma(n-r+1) or a suitable limit
+ throw (std::range_error("numeric::binomial(): don´t know how to evaluate that."));
+}
+
+/** Bernoulli number. The nth Bernoulli number is the coefficient of x^n/n!
+ * in the expansion of the function x/(e^x-1).
+ *
+ * @return the nth Bernoulli number (a rational number).
+ * @exception range_error (argument must be integer >= 0) */
+numeric bernoulli(numeric const & nn)
+{
+ if (!nn.is_integer() || nn.is_negative())
+ throw (std::range_error("numeric::bernoulli(): argument must be integer >= 0"));
+ if (nn.is_zero())
+ return numONE();
+ if (!nn.compare(numONE()))
+ return numeric(-1,2);
+ if (nn.is_odd())
+ return numZERO();
+ // Until somebody has the Blues and comes up with a much better idea and
+ // codes it (preferably in CLN) we make this a remembering function which
+ // computes its results using the formula
+ // B(nn) == - 1/(nn+1) * sum_{k=0}^{nn-1}(binomial(nn+1,k)*B(k))
+ // whith B(0) == 1.
+ static vector<numeric> results;
+ static int highest_result = -1;
+ int n = nn.sub(numTWO()).div(numTWO()).to_int();
+ if (n <= highest_result)
+ return results[n];
+ if (results.capacity() < (unsigned)(n+1))
+ results.reserve(n+1);
+
+ numeric tmp; // used to store the sum
+ for (int i=highest_result+1; i<=n; ++i) {
+ // the first two elements:
+ tmp = numeric(-2*i-1,2);
+ // accumulate the remaining elements:
+ for (int j=0; j<i; ++j)
+ tmp += binomial(numeric(2*i+3),numeric(j*2+2))*results[j];
+ // divide by -(nn+1) and store result:
+ results.push_back(-tmp/numeric(2*i+3));
}
- // return factorial(n).div(factorial(k).mul(factorial(n.sub(k))));
+ highest_result=n;
+ return results[n];
}
/** Absolute value. */
git://www.ginac.de / ginac.git / blobdiff