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Optimized divMod in poly

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Made a huge speed improvement in debug mode. Only a few % in release,
but the memory load should be somewhat lower.
This commit is contained in:
Robert Persson 2013-07-03 12:44:26 +02:00
commit ce1399db2d
1 changed files with 11 additions and 13 deletions
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24
lib/pure/poly.nim
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@ -12,6 +12,8 @@ import strutils
import numeric import numeric
import times #todo: remove
type type
TPoly* = object TPoly* = object
cofs:seq[float] cofs:seq[float]
@ -169,28 +171,25 @@ proc divMod*(p,d:TPoly;q,r:var TPoly)=
power=p.degree-d.degree power=p.degree-d.degree
ratio:float ratio:float
r.cofs = p.cofs #initial remainder=numerator
if power<0: #denominator is larger than numerator if power<0: #denominator is larger than numerator
q=initPoly(0.0) #division result is 0 q.cofs= @ [0.0] #quotinent is 0.0
r=p #remainder is numerator return # keep remainder as numerator
return
q=initPolyFromDegree(power) q.cofs=newSeq[float](power+1)
r=p
for i in countdown(pdeg,ddeg): for i in countdown(pdeg,ddeg):
ratio=r[i]/d[ddeg] ratio=r.cofs[i]/d.cofs[ddeg]
q[i-ddeg]=ratio q.cofs[i-ddeg]=ratio
r[i]=0.0 r.cofs[i]=0.0
for j in countup(0,<ddeg): for j in countup(0,<ddeg):
var idx=i-ddeg+j var idx=i-ddeg+j
r[idx] = r[idx] - d[j]*ratio r.cofs[idx] = r.cofs[idx] - d.cofs[j]*ratio
r.clean # drop zero coefficients in remainder r.clean # drop zero coefficients in remainder
proc `+` *(p1:TPoly,p2:TPoly):TPoly= proc `+` *(p1:TPoly,p2:TPoly):TPoly=
## Adds two polynomials ## Adds two polynomials
var n=max(p1.cofs.len,p2.cofs.len) var n=max(p1.cofs.len,p2.cofs.len)
@ -337,7 +336,7 @@ proc addRoot(p:TPoly,res:var seq[float],xp0,xp1,tol,zerotol,mergetol:float,maxit
proc roots*(p:TPoly,tol=1.0e-9,zerotol=1.0e-6,mergetol=1.0e-12,maxiter=1000):seq[float]= proc roots*(p:TPoly,tol=1.0e-9,zerotol=1.0e-6,mergetol=1.0e-12,maxiter=1000):seq[float]=
## Computes the real roots of the polynomial `p` ## Computes the real roots of the polynomial `p`
## `tol` is the tolerance use to break searching for each root when reached. ## `tol` is the tolerance used to break searching for each root when reached.
## `zerotol` is the tolerance, which is 'close enough' to zero to be considered a root ## `zerotol` is the tolerance, which is 'close enough' to zero to be considered a root
## and is used to find roots for curves that only 'touch' the x-axis. ## and is used to find roots for curves that only 'touch' the x-axis.
## `mergetol` is the tolerance, of which two x-values are considered beeing the same root. ## `mergetol` is the tolerance, of which two x-values are considered beeing the same root.
@ -365,5 +364,4 @@ proc roots*(p:TPoly,tol=1.0e-9,zerotol=1.0e-6,mergetol=1.0e-12,maxiter=1000):seq
range.xmin=x range.xmin=x
addRoot(p,result,range.xmin,range.xmax,tol,zerotol,mergetol,maxiter) addRoot(p,result,range.xmin,range.xmax,tol,zerotol,mergetol,maxiter)