test_erf = ->
run_test [
"erf(a)",
"erf(0.0) + 1",
"1.0",
"float(erf(0))",
"0.0",
"erf(0.0)",
"erf(-0.0)",
"erf(0)",
"0",
"erf(-0)",
"float(erf(0)) + 1",
"float(erf(1))",
"0.842701...",
]