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Approximately equal circuits with symbols not detected by cirq.approx_eq

See original GitHub issue

Description of the issue Circuits with symbols are determined to be unequal by cirq.approx_eq when they should be approximately equal.

How to reproduce the issue

q = cirq.GridQubit(0, 0)
s = sympy.Symbol("s")

no_symbol_1 = cirq.Circuit(cirq.rz(1.515)(q))
no_symbol_2 = cirq.Circuit(cirq.rz(1.510)(q))
print(cirq.approx_eq(no_symbol_1, no_symbol_2, atol=0.1))

symbol_1 = cirq.Circuit(cirq.rz(1.515*s)(q))
symbol_2 = cirq.Circuit(cirq.rz(1.510*s)(q))
print(cirq.approx_eq(symbol_1, symbol_2, atol=0.1))

First output is True, second output is False

Cirq version 0.8.2

Issue Analytics

State:
Created 3 years ago
Comments:5 (5 by maintainers)

Top GitHub Comments

1reaction

tonybruguier-googlecommented, Aug 5, 2020

Is help still needed on this? I am looking for a good first issue.

1reaction

balopatcommented, Aug 5, 2020

Thank you for filing this @zaqqwerty - this should work. Either approx_eq should throw an error if the arguments are parametrized that it’s not supported or support it properly. This behavior is a silent failure. Marked it as a bug.

It also seems like a self contained issue, perfect for contributors to pick up!

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