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| author | Gabriel Dos Reis <gdr@axiomatics.org> | 2015-12-31 14:56:12 -0800 |
|---|---|---|
| committer | Gabriel Dos Reis <gdr@axiomatics.org> | 2015-12-31 14:56:12 -0800 |
| commit | f51aee83708673ef9941174951bec9aee80cb03c (patch) | |
| tree | 4d8cfccd653dfa09819234bc61a8775091e4f1e6 /src/algebra/rep2.spad.pamphlet | |
| parent | 039d244dbef31e4ca6d34d2cf42b58b41a572884 (diff) | |
| download | open-axiom-f51aee83708673ef9941174951bec9aee80cb03c.tar.gz | |
Avoid modulus bias in 'random()' usage.
Diffstat (limited to 'src/algebra/rep2.spad.pamphlet')
| -rw-r--r-- | src/algebra/rep2.spad.pamphlet | 31 |
1 files changed, 11 insertions, 20 deletions
diff --git a/src/algebra/rep2.spad.pamphlet b/src/algebra/rep2.spad.pamphlet index 4219ab67..5524c72d 100644 --- a/src/algebra/rep2.spad.pamphlet +++ b/src/algebra/rep2.spad.pamphlet @@ -312,10 +312,10 @@ RepresentationPackage2(R): public == private where createRandomElement(aG,algElt) == numberOfGenerators : NNI := #aG -- randomIndex := randnum numberOfGenerators - randomIndex := 1+(random()$Integer rem numberOfGenerators) + randomIndex := 1 + random(numberOfGenerators)$Integer algElt := algElt * aG.randomIndex -- randomIndxElement := randnum numberOfGenerators - randomIndex := 1+(random()$Integer rem numberOfGenerators) + randomIndex := 1 + random(numberOfGenerators)$Integer algElt + aG.randomIndex @@ -481,8 +481,7 @@ RepresentationPackage2(R): public == private where -- fingerprint. x0,x1: M R if randomelements then -- random should not be from I - --randomIndex : I := randnum numberOfGenerators - randomIndex := 1+(random()$Integer rem numberOfGenerators) + randomIndex := 1 + random(numberOfGenerators)$Integer x0 := aG0.randomIndex x1 := aG1.randomIndex n : NNI := #row(x0,1) -- degree of representation @@ -496,12 +495,10 @@ RepresentationPackage2(R): public == private where -- chosen elements form "aG". if i = 7 then randomelements := true if randomelements then - --randomIndex := randnum numberOfGenerators - randomIndex := 1+(random()$Integer rem numberOfGenerators) + randomIndex := 1 + random(numberOfGenerators)$Integer x0 := x0 * aG0.randomIndex x1 := x1 * aG1.randomIndex - --randomIndex := randnum numberOfGenerators - randomIndex := 1+(random()$Integer rem numberOfGenerators) + randomIndex := 1 + random(numberOfGenerators)$Integer x0 := x0 + aG0.randomIndex x1 := x1 + aG1.randomIndex else @@ -576,8 +573,7 @@ RepresentationPackage2(R): public == private where result : B := false numberOfGenerators : NNI := #aG -- need a start value for creating random matrices: - -- randomIndex : I := randnum numberOfGenerators - randomIndex := 1+(random()$Integer rem numberOfGenerators) + randomIndex := 1 + random(numberOfGenerators)$Integer x : M R := aG.randomIndex n : NNI := #row(x,1) -- degree of representation foundResult : B := false @@ -587,11 +583,9 @@ RepresentationPackage2(R): public == private where -- create random elements recursively: -- x_i+1 :=x_i * mr1 + mr2, where mr1 and mr2 are randomly -- chosen elements form "aG". - -- randomIndex := randnum numberOfGenerators - randomIndex := 1+(random()$Integer rem numberOfGenerators) + randomIndex := 1 + random(numberOfGenerators)$Integer x := x * aG.randomIndex - --randomIndex := randnum numberOfGenerators - randomIndex := 1+(random()$Integer rem numberOfGenerators) + randomIndex := 1 + random(numberOfGenerators)$Integer x := x + aG.randomIndex -- test whether rank of x is n-1 rk : NNI := rank x @@ -672,8 +666,7 @@ RepresentationPackage2(R): public == private where -- if we switch to randomelements later, we take the last -- fingerprint. if randomelements then -- random should not be from I - --randomIndex : I := randnum numberOfGenerators - randomIndex := 1+(random()$Integer rem numberOfGenerators) + randomIndex := 1 + random(numberOfGenerators)$Integer x : M R := algebraGenerators.randomIndex foundResult : B := false for i in 1..numberOfTries until foundResult repeat @@ -685,11 +678,9 @@ RepresentationPackage2(R): public == private where -- chosen elements form "algebraGenerators". if i = 7 then randomelements := true if randomelements then - --randomIndex := randnum numberOfGenerators - randomIndex := 1+(random()$Integer rem numberOfGenerators) + randomIndex := 1 + random(numberOfGenerators)$Integer x := x * algebraGenerators.randomIndex - --randomIndex := randnum numberOfGenerators - randomIndex := 1+(random()$Integer rem numberOfGenerators) + randomIndex := 1 + random(numberOfGenerators)$Integer x := x + algebraGenerators.randomIndex else x := fingerPrint (i, algebraGenerators.1,_ |