# Differences

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 — documentation:language_reference:functions:chop [2016/10/10 09:41] (current) 2016/10/09 21:27 Maurits W. Haverkort created 2016/10/09 21:27 Maurits W. Haverkort created Line 1: Line 1: + ====== Chop ====== + ### + Chop(//a//) replaces approximate real numbers in //a// that are close to zero by the exact integer 0. Chop(//a//, $\epsilon$) replaces numbers smaller in absolute magnitude than $\epsilon$ by 0. Chop uses a default tolerance of $\epsilon=10^{-10}$. Chop works on Real and Complex numbers as well as on operators and wavefunctions. ​ + ### + + ===== Input ===== + + * //a// : object that will be chopped, all types allowed + * $\epsilon$ : real number setting the boundary between zero and finite + + ===== Output ===== + + * //a'// : object of same type as //a// + + ===== Example ===== + + ### + A small test script of chop is: + ### + + ==== Input ==== + ​ + dofile("​../​definitions.Quanty"​) + + Opp = Opp1 + 0.000001*Opp2 + print(Opp) + Opp3 = Chop(Opp,​0.001) + print(Opp3) + + psi = psi1 + 0.00001 * psi2 + print(psi) + psi3 = Chop(psi,​0.001) + print(psi3) + + a = 0.000001 + 0.3 * I + b = Chop(a,​0.001) + print("​a = ",​a,"​\nChop(a) = ",b) + ​ + + ==== Result ==== + ​ + + Operator: Lx + QComplex ​        ​= ​         1 (Real==0 or Complex==1 or Mixed==2) + MaxLength ​       =          2 (largest number of product of lader operators) + NFermionic modes =          6 (Number of fermionic modes (site, spin, orbital, ...) in the one particle basis) + NBosonic modes   ​= ​         0 (Number of bosonic modes (phonon modes, ...) in the one particle basis) + + Operator of Length ​  2 + QComplex ​     =          1 (Real==0 or Complex==1) + N             ​= ​         8 (number of operators of length ​  2) + C  3 A  1 |  7.071067811865476E-01 -7.071067811865476E-07 + C  1 A  3 |  7.071067811865476E-01 ​ 7.071067811865476E-07 + C  2 A  0 |  7.071067811865476E-01 -7.071067811865476E-07 + C  0 A  2 |  7.071067811865476E-01 ​ 7.071067811865476E-07 + C  5 A  3 |  7.071067811865476E-01 -7.071067811865476E-07 + C  3 A  5 |  7.071067811865476E-01 ​ 7.071067811865476E-07 + C  4 A  2 |  7.071067811865476E-01 -7.071067811865476E-07 + C  2 A  4 |  7.071067811865476E-01 ​ 7.071067811865476E-07 + + + + Operator: Lx + QComplex ​        ​= ​         0 (Real==0 or Complex==1 or Mixed==2) + MaxLength ​       =          2 (largest number of product of lader operators) + NFermionic modes =          6 (Number of fermionic modes (site, spin, orbital, ...) in the one particle basis) + NBosonic modes   ​= ​         0 (Number of bosonic modes (phonon modes, ...) in the one particle basis) + + Operator of Length ​  2 + QComplex ​     =          0 (Real==0 or Complex==1) + N             ​= ​         8 (number of operators of length ​  2) + C  3 A  1 |  7.071067811865476E-01 + C  1 A  3 |  7.071067811865476E-01 + C  2 A  0 |  7.071067811865476E-01 + C  0 A  2 |  7.071067811865476E-01 + C  5 A  3 |  7.071067811865476E-01 + C  3 A  5 |  7.071067811865476E-01 + C  4 A  2 |  7.071067811865476E-01 + C  2 A  4 |  7.071067811865476E-01 + + + + WaveFunction:​ Wave Function + QComplex ​        ​= ​         0 (Real==0 or Complex==1) + N                =          3 (Number of basis functions used to discribe psi) + NFermionic modes =          6 (Number of fermions in the one particle basis) + NBosonic modes   ​= ​         0 (Number of bosons in the one particle basis) + + #      pre-factor ​        ​Determinant + ​1 ​  ​3.162277660168E-01 ​      ​110000 + ​2 ​  ​9.486832980505E-01 ​      ​100010 + ​3 ​  ​1.000000000000E-05 ​      ​010010 + + + + WaveFunction:​ Wave Function + QComplex ​        ​= ​         0 (Real==0 or Complex==1) + N                =          2 (Number of basis functions used to discribe psi) + NFermionic modes =          6 (Number of fermions in the one particle basis) + NBosonic modes   ​= ​         0 (Number of bosons in the one particle basis) + + #      pre-factor ​        ​Determinant + ​1 ​  ​9.486832980505E-01 ​      ​100010 + ​2 ​  ​3.162277660168E-01 ​      ​110000 + + + a = (1e-06 + 0.3 I) + Chop(a) = (0 + 0.3 I) + + ​ + + ===== Table of contents ===== + {{indexmenu>​.#​1}}