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Incorrect Numeric Expression Syntax in QASM Export #6550

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p51lee opened this issue Apr 5, 2024 · 3 comments · May be fixed by #6802
Open

Incorrect Numeric Expression Syntax in QASM Export #6550

p51lee opened this issue Apr 5, 2024 · 3 comments · May be fixed by #6802
Labels
area/interop area/qasm kind/bug-report Something doesn't seem to work. triage/accepted there is consensus amongst maintainers that this is a real bug or a reasonable feature to add
Milestone
2025-T7: Ensure i...

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@p51lee
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p51lee commented Apr 5, 2024 •
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Description of the issue

image

The to_qasm method exports numeric expressions in a format not fully compliant with the OpenQASM 2.0 specification. Expressions like 1e-10 are outputted without a leading digit or dot, which could lead to syntax errors in strict OpenQASM parsers.

How to reproduce the issue

import math

cirq_circuit = cirq.Circuit()
a = cirq.NamedQubit("a")
cirq_circuit.append([cirq.Rz(rads=math.pi * 1e-10)(a)])
print(cirq_circuit.to_qasm())

Result

// Generated from Cirq v1.3.0

OPENQASM 2.0;
include "qelib1.inc";


// Qubits: [a]
qreg q[1];


rz(pi*1e-10) q[0];  // invalid syntax (expected: 1.e-10 or 1.0e-10)

Cirq version
1.3.0
@p51lee p51lee added the kind/bug-report Something doesn't seem to work. label Apr 5, 2024
@pavoljuhas pavoljuhas added the triage/accepted there is consensus amongst maintainers that this is a real bug or a reasonable feature to add label Apr 24, 2024
@verult
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verult commented Apr 24, 2024

From the Cirq Cync: we're planning to drop support for OpenQASM 2 and move to OpenQASM 3. Does the same issue apply in the new version?

@p51lee
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p51lee commented Apr 25, 2024

I'm working with the latest version and to_qasm method gives OpenQASM 2 code. Is there a parameter or a different method available that I should use to obtain OpenQASM 3 code instead?

@p51lee p51lee mentioned this issue May 28, 2024
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@dstrain115
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It looks like this is not a problem with OpenQASM 3.0, since the specification and grammar changed:

FloatLiteral:
    // 1_123e-3, 123e+4 or 123E5 (needs the exponent or it's just an integer)
    DecimalIntegerLiteral FloatLiteralExponent
    // .1234_5678 or .1e3 (no digits before the dot)
    | DOT DecimalIntegerLiteral FloatLiteralExponent?
    // 123.456, 123. or 145.32e+1_00
    | DecimalIntegerLiteral DOT DecimalIntegerLiteral? FloatLiteralExponent?;

However, I will see if I can fix this anyway, since I am updating openQASM

@dstrain115 dstrain115 linked a pull request Nov 19, 2024 that will close this issue
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Labels
area/interop area/qasm kind/bug-report Something doesn't seem to work. triage/accepted there is consensus amongst maintainers that this is a real bug or a reasonable feature to add
Projects
Cirq 2025 roadmap
Status: No status
Milestone
2025-T7: Ensure interoperability with...
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Successfully merging a pull request may close this issue.

Force decimals in scientific notation for OpenQASM 2.0 dstrain115/Cirq-1
5 participants
@mhucka @verult @pavoljuhas @dstrain115 @p51lee