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Matlab function assumed inputs

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Benjamin Wilson
Benjamin Wilson 2023-11-17
编辑： Stephen23 2023-11-17
Does Matlab support functions with inputs that if not given, can be assumed?
I would like to write some code similar to the following - where if alpha and beta are not given when calling the function they are assigned to a set value 10 and -0.1 respectively
function [x,y] = pricingprogramme(P,T,alpha = 10, beta = -0.1)
... some code using P,T aswell as alpha and beta ....
end
Any help would be greatly appreciated.

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采纳的回答

Dyuman Joshi
Dyuman Joshi 2023-11-17
Ran in:
Yes, use varargin with nargin -
[x1,y1] = pricingprogramme(5,10)
x1 = 16
y1 = 40.1000
[x2,y2] = pricingprogramme(1,2,3,4)
x2 = -9
y2 = -5
function [x,y] = pricingprogramme(P,T, varargin)
if nargin == 4
alpha = varargin{1};
beta = varargin{2};
elseif nargin==2
alpha = 10;
beta = -0.1;
else
%Modify other cases as per need
error('Number of inputs must be 2 or 4')
end
%Random definitions
x = P + T - alpha*beta;
y = P*T - (alpha + beta);
end

更多回答（3 个）

Stephen23
Stephen23 2023-11-17
编辑：Stephen23 2023-11-17
Ran in:
The simplest approach is to use the ARGUMENTS block:
https://www.mathworks.com/help/matlab/ref/arguments.html
https://www.mathworks.com/help/matlab/matlab_prog/function-argument-validation-1.html
pricingprogramme([],[])
ans = 10.1000
pricingprogramme([],[],3,0.5)
ans = 3.5000
function out = pricingprogramme(P,T,alpha,beta)
arguments
P
T
alpha = 10
beta = 0.1
end
out = alpha + beta;
end
Florian Bidaud
Florian Bidaud 2023-11-17
编辑：Florian Bidaud 2023-11-17
Hi,
if you want positional arguments, use addOptional with an inputParser like this :
% to use the function as
% [x,y] = pricingprogramme(P, T, alpha_value, beta_value)
% or pricingprogramme(P, T, alpha_value)
% or pricingprogramme(P, T)
function [x,y] = pricingprogramme(P,T,varargin)
p = inputParser;
addOptional(p,'alpha',10, @isnumeric)
addOptional(p,'beta',0.1, @isnumeric)
parse(p,varargin{:})
alpha = p.Results.alpha;
beta = p.Results.beta;
... some code using P,T aswell as alpha and beta ....
end
If you want to add them as parameters, use addParameter like this :
% to use the function as
% [x,y] = pricingprogramme(P, T, alpha=alpha_value, beta=beta_value)
% or pricingprogramme(P, T, alpha=alpha_value)
% or pricingprogramme(P, T, beta=beta_value)
% or pricingprogramme(P, T, beta=beta_value, alpha=alpha_value)
% or pricingprogramme(P, T)
function [x,y] = pricingprogramme(P,T,varargin)
p = inputParser;
addParameter(p,'alpha',10, @isnumeric)
addParameter(p,'beta',0.1, @isnumeric)
parse(p,varargin{:})
alpha = p.Results.alpha;
beta = p.Results.beta;
... some code using P,T aswell as alpha and beta ....
end
NOTE: @isnumeric is to check that the input value is a numeric value
madhan ravi
madhan ravi 2023-11-17
Use nargin() to determine if number of inputs are less than three assign the default values to alpha and beta else feed in the actual values of them

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