use L1 norm for drop tolerance (#27)

* use L1 norm for drop tolerance

* update CI

Author: stevengj

.github/workflows/CI.yml

@@ -23,24 +23,15 @@ jobs:
         arch:
           - x64
     steps:
-      - uses: actions/checkout@v2
-      - uses: julia-actions/setup-julia@v1
+      - uses: actions/checkout@v5
+      - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
-      - uses: actions/cache@v1
-        env:
-          cache-name: cache-artifacts
-        with:
-          path: ~/.julia/artifacts
-          key: ${{ runner.os }}-test-${{ env.cache-name }}-${{ hashFiles('**/Project.toml') }}
-          restore-keys: |
-            ${{ runner.os }}-test-${{ env.cache-name }}-
-            ${{ runner.os }}-test-
-            ${{ runner.os }}-
+      - uses: julia-actions/cache@v2
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-runtest@v1
       - uses: julia-actions/julia-processcoverage@v1
-      - uses: codecov/codecov-action@v1
+      - uses: codecov/codecov-action@v5
         with:
           file: lcov.info

src/interp.jl

@@ -72,7 +72,7 @@ infnorm(x::Number) = abs(x)
 infnorm(x::AbstractArray) = maximum(abs, x)
 
 function droptol(coefs::Array{<:Any,N}, tol::Real) where {N}
-    abstol = maximum(infnorm, coefs) * tol # absolute tolerance
+    abstol = sum(infnorm, coefs) * tol # absolute tolerance = L1 norm * tol
     all(c -> infnorm(c) ≥ abstol, coefs) && return coefs # nothing to drop
 
     # compute the new size along each dimension by checking