++ed by:
Kevin Ryde
and 1 contributors

# NAME

Math::NumSeq::DigitSumModulo -- digit sum taken modulo a given modulus

# SYNOPSIS

`````` use Math::NumSeq::DigitSumModulo;
my \$seq = Math::NumSeq::DigitSumModulo->new (radix => 10,
modulus => 9);
my (\$i, \$value) = \$seq->next;``````

# DESCRIPTION

The sum of digits in each i, taken modulo the radix or a given modulus. For example at i=123 with modulus 5 the value is 1+2+3=6, mod 5 = 1.

Modulus 0, which is the default, means modulo the radix.

## Thue-Morse Sequence

For `radix=>2, modulus=>2` this is the Thue-Morse "parity" sequence, being 1 if i has an odd number of 1 bits or 0 if an even number of 1 bits. Numbers where it's 1 are sometimes called "odious" numbers and where it's 0 called "evil" numbers.

# FUNCTIONS

See "FUNCTIONS" in Math::NumSeq for behaviour common to all sequence classes.

`\$seq = Math::NumSeq::DigitSumModulo->new (radix => \$r, modulus => \$d)`

Create and return a new sequence object.

## Random Access

`\$value = \$seq->ith(\$i)`

Return the sum of the digits in `\$i` written in `radix`, modulo the `modulus`.

`\$bool = \$seq->pred(\$value)`

Return true if `\$value` might occur as value in the sequence, which means simply `\$value `= 0> and `\$value <= modulus` (the given `modulus` or the `radix` if modulus=0).