squiggle.c/examples/08_nuclear_war/example.c

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#include "../../squiggle.h"
#include <math.h>
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#include <stdint.h>
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#include <stdio.h>
#include <stdlib.h>
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double probability_of_dying_nuno(uint64_t* seed)
{
double first_year_russian_nuclear_weapons = 1953;
double current_year = 2022;
double laplace_probability_nuclear_exchange_year = sample_beta(1, current_year - first_year_russian_nuclear_weapons + 1, seed);
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double laplace_probability_nuclear_exchange_month = 1 - pow(1 - laplace_probability_nuclear_exchange_year, (1.0 / 12.0));
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double london_hit_conditional_on_russia_nuclear_weapon_usage = sample_beta(7.67, 69.65, seed);
// I.e., a beta distribution with a range of 0.05 to 0.16 into: https://nunosempere.com/blog/2023/03/15/fit-beta/
// 0.05 were my estimate and Samotsvety's estimate in March 2022, respectively:
// https://forum.effectivealtruism.org/posts/KRFXjCqqfGQAYirm5/samotsvety-nuclear-risk-forecasts-march-2022#Nu_o_Sempere
double informed_actor_not_able_to_escape = sample_beta(3.26212166586967, 3.26228162008564, seed);
// 0.2 to 0.8, i.e., 20% to 80%, again using the previous tool
double proportion_which_die_if_bomb_drops_in_london = sample_beta(10.00, 2.45, seed); // 60% to 95%
double probability_of_dying = laplace_probability_nuclear_exchange_month * london_hit_conditional_on_russia_nuclear_weapon_usage * informed_actor_not_able_to_escape * proportion_which_die_if_bomb_drops_in_london;
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return probability_of_dying;
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}
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double probability_of_dying_eli(uint64_t* seed)
{
double russia_nato_nuclear_exchange_in_next_month = sample_beta(1.30, 1182.99, seed); // .0001 to .003
double london_hit_conditional = sample_beta(3.47, 8.97, seed); // 0.1 to 0.5
double informed_actors_not_able_to_escape = sample_beta(2.73, 5.67, seed); // .1 to .6
double proportion_which_die_if_bomb_drops_in_london = sample_beta(3.00, 1.46, seed); // 0.3 to 0.95;
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double probability_of_dying = russia_nato_nuclear_exchange_in_next_month * london_hit_conditional * informed_actors_not_able_to_escape * proportion_which_die_if_bomb_drops_in_london;
return probability_of_dying;
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}
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double mixture(uint64_t* seed)
{
double (*samplers[])(uint64_t*) = { probability_of_dying_nuno, probability_of_dying_eli };
double weights[] = { 0.5, 0.5 };
return sample_mixture(samplers, weights, 2, seed);
}
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int main()
{
// set randomness seed
uint64_t* seed = malloc(sizeof(uint64_t));
*seed = 1000; // xorshift can't start with 0
int n = 1000 * 1000;
double* mixture_result = malloc(sizeof(double) * n);
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for (int i = 0; i < n; i++) {
mixture_result[i] = mixture(seed);
}
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printf("mixture_result: [ ");
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for (int i = 0; i < 9; i++) {
printf("%.6f, ", mixture_result[i]);
}
printf("... ]\n");
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struct c_i c_i_90 = get_90_confidence_interval(mixture, seed);
printf("mean: %f\n", array_mean(mixture_result, n));
printf("90%% confidence interval: [%f, %f]\n", c_i_90.low, c_i_90.high);
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free(seed);
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}