nd4j-common/src/main/java/org/nd4j/linalg/util/BigDecimalMath.java
static public BigDecimal sqrt(final BigDecimal x) {
        if (x.compareTo(BigDecimal.ZERO) < 0) {
            throw new ArithmeticException("negative argument " + x.toString() + " of square root");
        }
        return root(2, x);
    }
static public BigDecimal sqrt(final BigDecimal x) {
        if (x.compareTo(BigDecimal.ZERO) < 0) {
            throw new ArithmeticException("negative argument " + x.toString() + " of square root");
        }
        return root(2, x);
    }
The square root.

@param x the non-negative argument.
@return the square root of the BigDecimal rounded to the precision implied by x.