@math:pow

Raise a fixed-point value to a whole power, where one unit is base (1e18 by default, 1e27 for a ray). Compounding a per-period rate over N periods is pow(unit + rate, N).

On-chain (@math:pow!): A value carrying a scale other than a wad must state its unit, since the plain face cannot see a scale and would compound at 1e18.

Returns: number

Syntax

@math:pow(value exponent base?)

Arguments

Name	Type	Description
value	number	The fixed-point value to raise
exponent	number	Whole exponent
[base]	number	One unit of the value, e.g. 1e18 or 1e27 (default: 1e18)

Examples

# Compound a 5% per-period rate over 12 periods, wad-scaled
set $growth @math:pow(1.05e18 12)
print $growth

See Also

On-chain face (@math:pow!)

Compiles to the Operators contract's rpow(x, n, base), the fixed-point exponentiation by squaring the rest of the fixed-point family uses.

Two things it refuses rather than answering:

• Signed operands. Both the value and the exponent must be unsigned.
• A scaled value whose unit it would have to guess. When the operand carries a scale of its own (a ray read, say) and no base argument is given, the on-chain face could take the unit from that scale — but a Num carries no scale, so the plain face cannot see it and always compounds at 1e18. The two faces would then disagree by orders of magnitude on the same source text, so the on-chain face asks for the unit instead: @pow!(value exponent 1e27). A wad-scaled operand needs no argument, since that is the default on both sides.

The base argument itself is resolved at composition time, so it must be a literal unit rather than a live read. When both the value and the exponent are constants the whole call folds at composition time and no read is emitted at all.