- unsigned result = 0;
- symbol x("x");
- ex chk;
-
- chk = asin(1)-acos(0);
- if (!chk.is_zero()) {
- clog << "asin(1)-acos(0) erroneously returned " << chk
- << " instead of 0" << endl;
- ++result;
- }
-
- // arbitrary check of type sin(f(x)):
- chk = pow(sin(acos(x)),2) + pow(sin(asin(x)),2)
- - (1+pow(x,2))*pow(sin(atan(x)),2);
- if (chk != 1-pow(x,2)) {
- clog << "sin(acos(x))^2 + sin(asin(x))^2 - (1+x^2)*sin(atan(x))^2 "
- << "erroneously returned " << chk << " instead of 1-x^2" << endl;
- ++result;
- }
-
- // arbitrary check of type cos(f(x)):
- chk = pow(cos(acos(x)),2) + pow(cos(asin(x)),2)
- - (1+pow(x,2))*pow(cos(atan(x)),2);
- if (!chk.is_zero()) {
- clog << "cos(acos(x))^2 + cos(asin(x))^2 - (1+x^2)*cos(atan(x))^2 "
- << "erroneously returned " << chk << " instead of 0" << endl;
- ++result;
- }
-
- // arbitrary check of type tan(f(x)):
- chk = tan(acos(x))*tan(asin(x)) - tan(atan(x));
- if (chk != 1-x) {
- clog << "tan(acos(x))*tan(asin(x)) - tan(atan(x)) "
- << "erroneously returned " << chk << " instead of -x+1" << endl;
- ++result;
- }
-
- // arbitrary check of type sinh(f(x)):
- chk = -pow(sinh(acosh(x)),2).expand()*pow(sinh(atanh(x)),2)
- - pow(sinh(asinh(x)),2);
- if (!chk.is_zero()) {
- clog << "expand(-(sinh(acosh(x)))^2)*(sinh(atanh(x))^2) - sinh(asinh(x))^2 "
- << "erroneously returned " << chk << " instead of 0" << endl;
- ++result;
- }
-
- // arbitrary check of type cosh(f(x)):
- chk = (pow(cosh(asinh(x)),2) - 2*pow(cosh(acosh(x)),2))
- * pow(cosh(atanh(x)),2);
- if (chk != 1) {
- clog << "(cosh(asinh(x))^2 - 2*cosh(acosh(x))^2) * cosh(atanh(x))^2 "
- << "erroneously returned " << chk << " instead of 1" << endl;
- ++result;
- }
-
- // arbitrary check of type tanh(f(x)):
- chk = (pow(tanh(asinh(x)),-2) - pow(tanh(acosh(x)),2)).expand()
- * pow(tanh(atanh(x)),2);
- if (chk != 2) {
- clog << "expand(tanh(acosh(x))^2 - tanh(asinh(x))^(-2)) * tanh(atanh(x))^2 "
- << "erroneously returned " << chk << " instead of 2" << endl;
- ++result;
- }
-
- return result;
+ // NOTE: this can safely be removed once CLN supports dilogarithms and
+ // checks them itself.
+ unsigned result = 0;
+ bool errorflag;
+
+ // check the relation Li2(z^2) == 2 * (Li2(z) + Li2(-z)) numerically, which
+ // should hold in the entire complex plane:
+ errorflag = false;
+ ex argument;
+ numeric epsilon(double(1e-16));
+ for (int n=0; n<200; ++n) {
+ argument = numeric(20.0*rand()/(RAND_MAX+1.0)-10.0)
+ + numeric(20.0*rand()/(RAND_MAX+1.0)-10.0)*I;
+ if (abs(Li2(pow(argument,2))-2*Li2(argument)-2*Li2(-argument)) > epsilon) {
+ clog << "Li2(z) at z==" << argument
+ << " failed to satisfy Li2(z^2)==2*(Li2(z)+Li2(-z))" << endl;
+ errorflag = true;
+ }
+ }
+
+ if (errorflag)
+ ++result;
+
+ return result;