clojure/clojure · error · IllegalArgumentException

Value out of range for float:

Error message

Value out of range for float: 

What it means

RT.floatCast(Object) narrows any Number to a Java float. If the number's double value exceeds Float.MAX_VALUE in magnitude, the narrowing would be lossy/infinite, so the runtime throws this IllegalArgumentException rather than producing Float/POSITIVE_INFINITY.

Solutions

1. Check range before casting: only cast when (<= (- Float/MAX_VALUE) n Float/MAX_VALUE).
2. Use doubles instead of floats if the magnitude legitimately exceeds float range.
3. Clamp the value: (float (max (- Float/MAX_VALUE) (min Float/MAX_VALUE n))) if saturation is acceptable.
4. Catch IllegalArgumentException if out-of-range floats are expected and handle them explicitly.

Example fix

// before
(def f (float x)) ;; throws when x = 1e50
// after
(def f (if (<= (- Float/MAX_VALUE) x Float/MAX_VALUE)
         (float x)
         (throw (ex-info "cannot represent as float" {:x x}))))

(defn safe-float-cast [x]
  (when (and (number? x) (<= (- Float/MAX_VALUE) x Float/MAX_VALUE))
    (float x)))

(defn float-representable? [x]
  (and (number? x) (<= (Math/abs (double x)) Float/MAX_VALUE)))

(try (float x)
  (catch IllegalArgumentException _
    (throw (ex-info "value not representable as float" {:value x}))))

When it happens

Trigger: Calling (float x) / RT.floatCast on a Number (Double, BigDecimal, BigInt, Long) whose doubleValue() is outside [-Float.MAX_VALUE, Float.MAX_VALUE], e.g. (float 1e50).

Common situations: Converting large doubles or BigInts to float for interop with float-typed Java APIs, math on large values then cast to float, reading oversized numeric fields from data files.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• Value out of range for int:
• Value out of range for long:
• Value out of range for short:
• AbortException
• Accessor/struct mismatch

AI-assisted analysis of clojure/clojure@f3b143341d (2026-09-09). Data as JSON: /api/errors/a0053d69f12ff71c. Report an issue: GitHub.

Appendix: source

Thrown at src/jvm/clojure/lang/RT.java:1313

}

static public long longCast(long x){
	return x;
}

static public long longCast(double x){
	if(x < Long.MIN_VALUE || x > Long.MAX_VALUE)
		throw new IllegalArgumentException("Value out of range for long: " + x);
	return (long) x;
}

static public float floatCast(Object x){
	if(x instanceof Float)
		return ((Float) x).floatValue();

	double n = ((Number) x).doubleValue();
	if(n < -Float.MAX_VALUE || n > Float.MAX_VALUE)
		throw new IllegalArgumentException("Value out of range for float: " + x);

	return (float) n;

}

static public float floatCast(byte x){
    return x;
}

static public float floatCast(short x){
    return x;
}

static public float floatCast(int x){
	return x;
}

static public float floatCast(float x){

View on GitHub (pinned to f3b143341d)