src/sage/symbolic/integration/integral.py: better giac errors #40405
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Perhaps too much work to implement, but perhaps consider specifying the error message to: "Optional backend for requested integration method not installed". When the error condition arises, the system would recognize that the "algorithm" is not in the recognized list but is in the wider "optional" list, so that a more specific error can be raised. |
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That's not too hard to do if we change the giac integrator to throw a I haven't re-run all of the integration tests but hopefully nothing breaks in CI. |
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Deleted a failing doctest to fix the CI. The situation now is actually slightly improved: to check if an indefinite integral backend worked or not, we are checking for "integral()" or "integrate()" in the resulting expression. We always get a partial answer from maxima in the test I removed, but when giac is not installed, we see the maxima result as a failure and proceed to try giac, which is a no-op, but is the last engine that does not raise an error. So, ultimately, we throw out the partially evaluated answer for a completely unevaluated one. I don't think the test is demonstrating anything terribly important (the very next test shows a partial answer from maxima) so I've simply removed the failing one. |
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Remaining CI issues appear unrelated, but beware that I am unable to test with sagemath-giac installed (giac no longer builds on Gentoo, and no one is going to fix it.) I don't know if we have a CI runner with the optional package installed. |
Make it possible to disable the documentation build by passing, $ meson setup -Dbuild-docs=false (Otherwise the documentation will be built by default, as usual.) This creates a new file "meson.options" at the top level where further options like "build-docs" will live.
Several libraries are detected at setup time, and the corresponding feature is enabled or disabled based on the library's presence. This commit retains this behavior by default while making it possible to explicitly enable or disable the feature via, $ meson setup -Dfoo=disabled or $ meson setup -Dfoo=enabled The former disables the feature even if the library is installed, and the latter makes it an error if the library is not installed. The list of features (valid values for foo) is, * bliss * brial * coxeter3 * mcqd * meataxe * rankwidth * sirocco * tdlib
We should only fall back to a compiler test for libec if pkg-config fails. Before this commit we were overriding the pkg-config result with the result of the compiler test.
Add examples of explicit configuration using the "-Doption=value" syntax, and mention the auto_features option for package maintainers.
Mention how to disabled wrapped subprojects in the tips for package maintainers section.
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If the optional sagemath-giac is not installed, requesting integration via giac "does nothing," i.e. sage: integrate(sin(x), x, algorithm="giac") integrate(sin(x), x) This is due mainly to the fact that, when no algorithm is requested, ALL available integration routines are tried one after the other. Having the giac integrator do nothing so that the problem can be handed to the next integrator makes sense. However, when algorithm="giac" is explicitly requested, this is confusing. This commit adds "giac" and "libgiac" to the chain of integration backends only when sagemath-giac is present. The end result is that passing algorithm="giac" to integrate() or integral() will raise an error about the missing feature rather than quietly doing nothing with the input: FeatureNotPresentError: sage.libs.giac is not available. Optional backend for giac integration not installed. No equivalent system packages for gentoo are known to Sage.
First, mention that both algorithm="giac" and algorithm="libgiac" require the optional sagemath-giac package to be installed. Then, clarify that the default algorithm is None, and has special behavior.
We have a doctest that is testing for an unevaluated integral: sage: A = integral(1/ ((x-4) * (x^4+x+1)), x); A integrate(1/((x^4 + x + 1)*(x - 4)), x) This is now failing because we output the maxima answer, -1/261*integrate((x^3 + 4*x^2 + 16*x + 65)/(x^4 + x + 1), x) + 1/261*log(x - 4) rather than the giac answer, which is completely unevaluated. In an earlier commit, giac was removed from the default list of integration backends whenever giac is not actually installed because this produces better error messages. But, as a side effect, we are no longer skipping over the partial maxima answer to accept the unevaluated giac answer. (This is actually an improvement in the case where giac is not installed and where sympy raises an error.) There is no important result tested by these lines, so I think the least confusing thing to do is re-word the surrounding paragraph a bit and delete this test. There are still other tests nearby for partial evaluation of hard integrals.
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If the optional sagemath-giac is not installed, requesting integration via giac "does nothing," i.e.
This is due mainly to the fact that, when no algorithm is requested, all available integration routines are tried one after the other. Having the giac integrator do nothing so that the problem can be handed to the next integrator makes sense.
However, when algorithm="giac" is explicitly requested, this is confusing. This commit inserts libgiac into the default chain of integrators only when sagemath-giac is present. The end result is that passing algorithm="giac" to
integrate()orintegral()will raise an error about the missing feature rather than quietly doing nothing with the input: