| 5 | 1/1 | 返回列表 |
| 查看: 2008 | 回復(fù): 6 | ||
| 當(dāng)前只顯示滿足指定條件的回帖,點(diǎn)擊這里查看本話題的所有回帖 | ||
[求助]
就是SVM的BPA求解算法!。!誰能給我把這段偽代碼,寫成程序。。。
|
||
|
This appendix shows the pseudo-code for the training is shown below. The algorithm is a model-trust algorithm based on the Levenberg-Marquardt algorithm [17]. Input parameters: out = array of SVM outputs SVM的輸出 target = array of booleans: is ith example a positive example?(0,1) priorl = number of positive examples prior0 = number of negative examples Outputs: A, B = parameters of sigmoid A = 0 B = log((prior0+l)/(priorl+l)) hiTarget = (priorl+l)/(priorl+2) yi為+1時(shí) loTarget = l/(prior0+2) yi為-1時(shí) lambda = le-3 olderr = le300 pp = temp array to store current estimate of probability of examples set all pp array elements to (priorl+l)/(prior0+priorl+2) count = 0 for it = l to l00 { a = 0, b = 0, c = 0, d = 0, e = 0 // First, compute Hessian & gradient of error function // with respect to A & B for i = l to len { if (target) t = hiTarget else t = loTarget dl = pp-t d2 = pp*(l-pp) a += out*out*d2 b += d2 c += out*d2 d += out*dl e += dl } // If gradient is really tiny, then stop if (abs(d) < 1e-9 && abs(e) < 1e-9) break oldA = A oldB = B err = 0 // Loop until goodness of fit increases while (1) { det = (a+lambda)*(b+lambda)-c*c if (det == 0) { // if determinant of Hessian is zero, // increase stabilizer lambda *= 10 continue } A = oldA + ((b+lambda)*d-c*e)/det B = oldB + ((a+lambda)*e-c*d)/det // Now, compute the goodness of fit err = 0; for i = 1 to len { p = 1/(1+exp(out*A+B)) pp = p // At this step, make sure log(0) returns -200 err -= t*log(p)+(1-t)*log(1-p) } if (err < olderr*(1+1e-7)) { lambda *= 0.1 break } // error did not decrease: increase stabilizer by factor of 10 // & try again lambda *= 10 if (lambda >= 1e6) // something is broken. Give up break } diff = err-olderr scale = 0.5*(err+olderr+1) if (diff > -1e-3*scale && diff < 1e-7*scale) count++ else count = 0 olderr = err if (count == 3) break } 真心求助。 |
鐵蟲 (正式寫手)


| 最具人氣熱帖推薦 [查看全部] | 作者 | 回/看 | 最后發(fā)表 | |
|---|---|---|---|---|
|
[考研] 一志愿吉林大學(xué)材料學(xué)碩321求調(diào)劑 +5 | Ymlll 2026-03-18 | 8/400 |
|
|---|---|---|---|---|
|
[考研] 274求調(diào)劑 +6 | S.H1 2026-03-18 | 6/300 |
|
|
[考研] 能源材料化學(xué)課題組招收碩士研究生8-10名 +4 | 脫穎而出 2026-03-16 | 11/550 |
|
|
[考研] 311求調(diào)劑 +4 | 冬十三 2026-03-18 | 4/200 |
|
|
[考研] 085601材料工程專碩求調(diào)劑 +6 | 慕寒mio 2026-03-16 | 6/300 |
|
|
[考研] 材料專碩306英一數(shù)二 +10 | z1z2z3879 2026-03-16 | 13/650 |
|
|
[考研] 0703化學(xué)求調(diào)劑 總分331 +3 | ZY-05 2026-03-13 | 3/150 |
|
|
[考研] 考研求調(diào)劑 +3 | 橘頌. 2026-03-17 | 4/200 |
|
|
[考研] 268求調(diào)劑 +7 | 好運(yùn)連綿不絕 2026-03-12 | 8/400 |
|
|
[考研] 材料與化工專碩調(diào)劑 +5 | heming3743 2026-03-16 | 5/250 |
|
|
[考研] 考研調(diào)劑 +3 | 淇ya_~ 2026-03-17 | 5/250 |
|
|
[考研] 283求調(diào)劑 +3 | 聽風(fēng)就是雨; 2026-03-16 | 3/150 |
|
|
[考研] 318求調(diào)劑 +3 | Yanyali 2026-03-15 | 3/150 |
|
|
[考研] 085600調(diào)劑 +5 | 漾漾123sun 2026-03-12 | 6/300 |
|
|
[考博] 東華理工大學(xué)化材專業(yè)26屆碩士博士申請(qǐng) +6 | zlingli 2026-03-13 | 6/300 |
|
|
[考研] 294求調(diào)劑 +3 | Zys010410@ 2026-03-13 | 4/200 |
|
|
[考研] 289求調(diào)劑 +4 | 這么名字咋樣 2026-03-14 | 6/300 |
|
|
[考研] 265求調(diào)劑 +4 | 威化餅07 2026-03-12 | 4/200 |
|
|
[考研] 復(fù)試調(diào)劑 +3 | 呼呼?~+123456 2026-03-14 | 3/150 |
|
|
[考研] 考研調(diào)劑 +4 | 芬達(dá)46 2026-03-12 | 4/200 |
|