The avatar for @dkirkby
David Kirkby
Public
DESI
Edited
Mar 27
2
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
function fitPrunedKnotsDiscontinuous(iknots, { mu=2 } = {}) {
const n = iknots.length - 1;
const backptr = new Array(n + 1).fill(-1);
const min_cost = new Array(n + 1).fill(Infinity);
min_cost[0] = 0;
for(let i2=1; i2 < n+1; ++i2) {
for(let i1=0; i1 < i2; ++i1) {
const sfit = segmentFit(iknots[i1], iknots[i2]);
const ndata = breaks[iknots[i2]] - breaks[iknots[i1]];
let cost = sfit.chisq / ndata;
if(i1 > 0) cost += min_cost[i1] + mu / iknots.length;
if(cost < min_cost[i2]) {
min_cost[i2] = cost;
backptr[i2] = i1;
}
}
}
const pruned = [ ];
let j = n;
while(j != -1) {
pruned.push(iknots[j]);
j = backptr[j];
}
pruned.reverse();
// Tabulate the fit for each wavelength.
const offset = index * arraySize;
let logw_lo, logw_hi = kwave[pruned[0]], chisq_sum = 0;
const fit = [ ];
for(let i = 0; i < pruned.length - 1; ++i) {
const sfit = segmentFit(pruned[i], pruned[i+1]);
logw_lo = logw_hi;
logw_hi = kwave[pruned[i+1]];
for(let k = breaks[pruned[i]]; k < breaks[pruned[i+1]]; ++k) {
const linear = sfit.linear(logwave[k]);
const chisq = ivar[offset + k] * (flux[offset + k] - linear) ** 2;
if(!Number.isFinite(chisq)) console.log(k, fullwave[k], i, sfit);
chisq_sum += chisq;
fit.push({ wlen:fullwave[k], linear, chisq });
}
}
return { pruned, fit, chisq_sum };
}
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell

One platform to build and deploy the best data apps

Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.
Learn more