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Sigmas math #1

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d694959
main.cpp: add simple sigmas math
vmobilis Jun 1, 2025
31b5c43
stable-diffusion.cpp: sigmas math propagation
vmobilis Jun 1, 2025
a08381b
stable-diffusion.cpp: typo
vmobilis Jun 2, 2025
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25 changes: 24 additions & 1 deletion examples/cli/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -657,12 +657,32 @@ void parse_args(int argc, const char** argv, SDParams& params) {

std::stringstream ss(sigmas_str);
std::string item;
unsigned char op;
float last_sigma, parsed_sigma;
while(std::getline(ss, item, ',')) {
item.erase(0, item.find_first_not_of(" \t\n\r\f\v"));
item.erase(item.find_last_not_of(" \t\n\r\f\v") + 1);
if (!item.empty()) {
try {
params.custom_sigmas.push_back(std::stof(item));
op = item[0]; // basic math handling
switch (op) {
case '+': case '-': case '*': case '/': case '^':
item.erase(0, 1); // "* 1.5" => "1.5"
item.erase(0, item.find_first_not_of(" \t\n\r\f\v"));
break;
default:
op = 0; // simply a value, or ignore unknown ops
}
parsed_sigma = (!item.empty()) ? std::stof(item) : 0.f;
switch (op) {
case '+': last_sigma += parsed_sigma; break;
case '-': last_sigma -= parsed_sigma; break;
case '*': last_sigma *= parsed_sigma; break;
case '/': last_sigma /= parsed_sigma; break;
case '^': last_sigma = std::pow(last_sigma, parsed_sigma); break;
default: last_sigma = parsed_sigma; // set as is
}
params.custom_sigmas.push_back(last_sigma);
} catch (const std::invalid_argument& e) {
fprintf(stderr, "error: invalid float value '%s' in --sigmas\n", item.c_str());
invalid_arg = true;
Expand All @@ -680,6 +700,9 @@ void parse_args(int argc, const char** argv, SDParams& params) {
invalid_arg = true;
break;
}
// use last 2 values as last op holder
params.custom_sigmas.push_back((float)op);
params.custom_sigmas.push_back(parsed_sigma);
} else {
fprintf(stderr, "error: unknown argument: %s\n", arg.c_str());
print_usage(argc, argv);
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22 changes: 19 additions & 3 deletions stable-diffusion.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1199,11 +1199,27 @@ static std::vector<float> prepare_sigmas(
std::vector<float> sigmas_for_generation;
if (custom_sigmas_count > 0 && custom_sigmas_arr != nullptr) {
LOG_INFO("Using custom sigmas provided by user for %s.", mode_name);
sigmas_for_generation.assign(custom_sigmas_arr, custom_sigmas_arr + custom_sigmas_count);
sigmas_for_generation.assign(custom_sigmas_arr, custom_sigmas_arr + custom_sigmas_count - 2); // last 2 values hold operation + operand
unsigned u = sigmas_for_generation.size();
size_t target_len = static_cast<size_t>(sample_steps) + 1;
if (sigmas_for_generation.size() < target_len) {
LOG_DEBUG("Custom sigmas count (%zu) is less than target steps + 1 (%zu). Padding with 0.0f.", sigmas_for_generation.size(), target_len);
if (u < target_len) {
unsigned char op = custom_sigmas_arr[u];
float last_parsed_sigma = custom_sigmas_arr[u + 1];
LOG_DEBUG("Custom sigmas count (%zu) is less than target steps + 1 (%zu). Propagating last operation (%c%f).", u, target_len, op, last_parsed_sigma);
sigmas_for_generation.resize(target_len, 0.0f);
for (; u < target_len - 1; u++) { // last sigma will be zeroed anyway
switch(op) {
case '+': sigmas_for_generation[u] = sigmas_for_generation[u - 1] + last_parsed_sigma; break;
case '-': sigmas_for_generation[u] = sigmas_for_generation[u - 1] - last_parsed_sigma; break;
case '*': sigmas_for_generation[u] = sigmas_for_generation[u - 1] * last_parsed_sigma; break;
case '/': sigmas_for_generation[u] = sigmas_for_generation[u - 1] / last_parsed_sigma; break;
case '^': sigmas_for_generation[u] = std::pow(sigmas_for_generation[u - 1], last_parsed_sigma); break;
default: sigmas_for_generation[u] = last_parsed_sigma;
}
}
for (u = 0; u < target_len; u++) {
LOG_DEBUG("sigmas_for_generation[%u] = '%f'.", u, sigmas_for_generation[u]);
}
} else if (sigmas_for_generation.size() > target_len) {
LOG_DEBUG("Custom sigmas count (%zu) is greater than target steps + 1 (%zu). Truncating.", sigmas_for_generation.size(), target_len);
sigmas_for_generation.resize(target_len);
Expand Down