fzero returns "Too many input arguments"

Function code:

function retf = f(pH, L, bl1, bl2, bl3, bh2, bh1, Ltot, MLratio)
  Mtot = MLratio * Ltot;
  H = 10^(-pH);
  M = Mtot / (1 + bl1*L + bl2*bl1*L^2 + bl3*bl2*bl1*L^3);
  Ltot_calculated = L + bl1*M*L + 2*bl2*bl1*M*L^2 + 3*bl3*bl2*bl1*M*L^3 + bh2*H^2*L + bh1*H*L;
  retf = Ltot - Ltot_calculated;
end

Want to optimize retf to 0 at specified pH values by varying L

clear all vars
clc

bl1 = 10^(6.78);
bl2 = 10^(11.78);
bl3 = 10^(14.9);
bh2 = 10^(15.9);
bh1 = 10^(9.83);
Ltot = 0.04;
MLratio = 1/3;

'speciation_ni_his_varied_pH_function.m';

fun = @(L)f(7, L, bl1, bl2, bl3, bh2, bh1, Ltot, MLratio);
[L, fval, info, output] = fzero(fun, [0, Ltot]);
L / Ltot

L is an element of 0:Ltot

Answer 1

[Star Strider]

Perhaps the order in the code is wrong. The functions must all be at the end of the script for included functions to work.

This runs without error when I run i t here —

bl1 = 10^(6.78);
bl2 = 10^(11.78);
bl3 = 10^(14.9);
bh2 = 10^(15.9);
bh1 = 10^(9.83);
Ltot = 0.04;
MLratio = 1/3;

'speciation_ni_his_varied_pH_function.m';

fun = @(L)f(7, L, bl1, bl2, bl3, bh2, bh1, Ltot, MLratio);
[L, fval, info, output] = fzero(fun, [0, Ltot]);
L / Ltot

ans = 9.5868e-09

function retf = f(pH, L, bl1, bl2, bl3, bh2, bh1, Ltot, MLratio)
Mtot = MLratio * Ltot;
H = 10^(-pH);
M = Mtot / (1 + bl1*L + bl2*bl1*L^2 + bl3*bl2*bl1*L^3);
Ltot_calculated = L + bl1*M*L + 2*bl2*bl1*M*L^2 + 3*bl3*bl2*bl1*M*L^3 + bh2*H^2*L + bh1*H*L;
retf = Ltot - Ltot_calculated;
end

Experiment to get different results.

.

[Danny Darby]

You got it. Thanks!

[Star Strider]

As always, my pleasure!

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