[GiNaC-devel] [PATCH 1/8] inifcns_nstdsums.cpp: S_num takes cl_N as an argument instead of numeric.
Alexei Sheplyakov
varg at theor.jinr.ru
Wed Mar 19 10:24:36 CET 2008
Implicit conversion from cl_N to numeric considered harmful.
Using GiNaC::numeric for numerical computations incurs significant
overhead, so one might want to do these computations using proper CLN
types. Unfortunately, it's not easy due to automatic conversion from
cln::cl_N to GiNaC::numeric. Here is a simple example:
cl_N x, y;
// initialize them
return sin(x) + y*exp(y);
The compiler complains about ambigously overloaded of functions, i.e.
cl_N cln::sin(const cl_N&) versus numeric GiNaC::sin(const numeric&).
Hence, I propose to disable *implicit* conversion from cl_N to numeric
(this can be done by marking the numeric ctor as `explicit').
However, this change happens to be a bit nontrivial, because that evil
conversion is used in GiNaC itself. So, I decided to rewrite those fragments
of code.
---
ginac/inifcns_nstdsums.cpp | 50 ++++++++++++++++++++++++++-----------------
1 files changed, 30 insertions(+), 20 deletions(-)
diff --git a/ginac/inifcns_nstdsums.cpp b/ginac/inifcns_nstdsums.cpp
index cd3511a..ea42a6e 100644
--- a/ginac/inifcns_nstdsums.cpp
+++ b/ginac/inifcns_nstdsums.cpp
@@ -320,7 +320,7 @@ cln::cl_N Lin_do_sum_Xn(int n, const cln::cl_N& x)
// forward declaration needed by function Li_projection and C below
-numeric S_num(int n, int p, const numeric& x);
+const cln::cl_N S_num(int n, int p, const cln::cl_N& x);
// helper function for classical polylog Li
@@ -371,7 +371,7 @@ cln::cl_N Li_projection(int n, const cln::cl_N& x, const cln::float_format_t& pr
} else {
cln::cl_N result = -cln::expt(cln::log(x), n-1) * cln::log(1-x) / cln::factorial(n-1);
for (int j=0; j<n-1; j++) {
- result = result + (S_num(n-j-1, 1, 1).to_cl_N() - S_num(1, n-j-1, 1-x).to_cl_N())
+ result = result + (S_num(n-j-1, 1, 1) - S_num(1, n-j-1, 1-x))
* cln::expt(cln::log(x), j) / cln::factorial(j);
}
return result;
@@ -402,7 +402,7 @@ numeric Lin_numeric(int n, const numeric& x)
cln::cl_N x_ = ex_to<numeric>(x).to_cl_N();
cln::cl_N result = -cln::expt(cln::log(x_), n-1) * cln::log(1-x_) / cln::factorial(n-1);
for (int j=0; j<n-1; j++) {
- result = result + (S_num(n-j-1, 1, 1).to_cl_N() - S_num(1, n-j-1, 1-x_).to_cl_N())
+ result = result + (S_num(n-j-1, 1, 1) - S_num(1, n-j-1, 1-x_))
* cln::expt(cln::log(x_), j) / cln::factorial(j);
}
return result;
@@ -1715,10 +1715,10 @@ cln::cl_N C(int n, int p)
if (k == 0) {
if (n & 1) {
if (j & 1) {
- result = result - 2 * cln::expt(cln::pi(),2*j) * S_num(n-2*j,p,1).to_cl_N() / cln::factorial(2*j);
+ result = result - 2 * cln::expt(cln::pi(),2*j) * S_num(n-2*j,p,1) / cln::factorial(2*j);
}
else {
- result = result + 2 * cln::expt(cln::pi(),2*j) * S_num(n-2*j,p,1).to_cl_N() / cln::factorial(2*j);
+ result = result + 2 * cln::expt(cln::pi(),2*j) * S_num(n-2*j,p,1) / cln::factorial(2*j);
}
}
}
@@ -1726,23 +1726,23 @@ cln::cl_N C(int n, int p)
if (k & 1) {
if (j & 1) {
result = result + cln::factorial(n+k-1)
- * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1).to_cl_N()
+ * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1)
/ (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
}
else {
result = result - cln::factorial(n+k-1)
- * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1).to_cl_N()
+ * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1)
/ (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
}
}
else {
if (j & 1) {
- result = result - cln::factorial(n+k-1) * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1).to_cl_N()
+ result = result - cln::factorial(n+k-1) * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1)
/ (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
}
else {
result = result + cln::factorial(n+k-1)
- * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1).to_cl_N()
+ * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1)
/ (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
}
}
@@ -1855,7 +1855,7 @@ cln::cl_N S_projection(int n, int p, const cln::cl_N& x, const cln::float_format
res2 = res2 + cln::expt(cln::cl_I(-1),r) * cln::expt(cln::log(1-x),r)
* S_do_sum(p-r,n-s,1-x,prec) / cln::factorial(r);
}
- result = result + cln::expt(cln::log(x),s) * (S_num(n-s,p,1).to_cl_N() - res2) / cln::factorial(s);
+ result = result + cln::expt(cln::log(x),s) * (S_num(n-s,p,1) - res2) / cln::factorial(s);
}
return result;
@@ -1866,7 +1866,7 @@ cln::cl_N S_projection(int n, int p, const cln::cl_N& x, const cln::float_format
// helper function for S(n,p,x)
-numeric S_num(int n, int p, const numeric& x)
+const cln::cl_N S_num(int n, int p, const cln::cl_N& x)
{
if (x == 1) {
if (n == 1) {
@@ -1902,11 +1902,11 @@ numeric S_num(int n, int p, const numeric& x)
// what is the desired float format?
// first guess: default format
cln::float_format_t prec = cln::default_float_format;
- const cln::cl_N value = x.to_cl_N();
+ const cln::cl_N value = x;
// second guess: the argument's format
- if (!x.real().is_rational())
+ if (!instanceof(realpart(value), cln::cl_RA_ring))
prec = cln::float_format(cln::the<cln::cl_F>(cln::realpart(value)));
- else if (!x.imag().is_rational())
+ else if (!instanceof(imagpart(value), cln::cl_RA_ring))
prec = cln::float_format(cln::the<cln::cl_F>(cln::imagpart(value)));
// [Kol] (5.3)
@@ -1919,9 +1919,9 @@ numeric S_num(int n, int p, const numeric& x)
cln::cl_N res2;
for (int r=0; r<p; r++) {
res2 = res2 + cln::expt(cln::cl_I(-1),r) * cln::expt(cln::log(1-value),r)
- * S_num(p-r,n-s,1-value).to_cl_N() / cln::factorial(r);
+ * S_num(p-r,n-s,1-value) / cln::factorial(r);
}
- result = result + cln::expt(cln::log(value),s) * (S_num(n-s,p,1).to_cl_N() - res2) / cln::factorial(s);
+ result = result + cln::expt(cln::log(value),s) * (S_num(n-s,p,1) - res2) / cln::factorial(s);
}
return result;
@@ -1936,7 +1936,7 @@ numeric S_num(int n, int p, const numeric& x)
for (int r=0; r<=s; r++) {
result = result + cln::expt(cln::cl_I(-1),s) * cln::expt(cln::log(-value),r) * cln::factorial(n+s-r-1)
/ cln::factorial(r) / cln::factorial(s-r) / cln::factorial(n-1)
- * S_num(n+s-r,p-s,cln::recip(value)).to_cl_N();
+ * S_num(n+s-r,p-s,cln::recip(value));
}
}
result = result * cln::expt(cln::cl_I(-1),n);
@@ -1972,12 +1972,18 @@ numeric S_num(int n, int p, const numeric& x)
static ex S_evalf(const ex& n, const ex& p, const ex& x)
{
if (n.info(info_flags::posint) && p.info(info_flags::posint)) {
+ const int n_ = ex_to<numeric>(n).to_int();
+ const int p_ = ex_to<numeric>(p).to_int();
if (is_a<numeric>(x)) {
- return S_num(ex_to<numeric>(n).to_int(), ex_to<numeric>(p).to_int(), ex_to<numeric>(x));
+ const cln::cl_N x_ = ex_to<numeric>(x).to_cl_N();
+ const cln::cl_N result = S_num(n_, p_, x_);
+ return numeric(result);
} else {
ex x_val = x.evalf();
if (is_a<numeric>(x_val)) {
- return S_num(ex_to<numeric>(n).to_int(), ex_to<numeric>(p).to_int(), ex_to<numeric>(x_val));
+ const cln::cl_N x_val_ = ex_to<numeric>(x_val).to_cl_N();
+ const cln::cl_N result = S_num(n_, p_, x_val_);
+ return numeric(result);
}
}
}
@@ -2002,7 +2008,11 @@ static ex S_eval(const ex& n, const ex& p, const ex& x)
return Li(n+1, x);
}
if (x.info(info_flags::numeric) && (!x.info(info_flags::crational))) {
- return S_num(ex_to<numeric>(n).to_int(), ex_to<numeric>(p).to_int(), ex_to<numeric>(x));
+ int n_ = ex_to<numeric>(n).to_int();
+ int p_ = ex_to<numeric>(p).to_int();
+ const cln::cl_N x_ = ex_to<numeric>(x).to_cl_N();
+ const cln::cl_N result = S_num(n_, p_, x_);
+ return numeric(result);
}
}
if (n.is_zero()) {
--
1.5.4.2
--
All science is either physics or stamp collecting.
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