How to set input in a dynamic way, by means of indirect references to an object or other variable

Hello to everybody,

I created a curve object "CurveName" with IRDataCurve and then I derived a rate structure from it by using toRateSpec function. Since I have several curves to choose among depending on the type of instrument to calculate the present value for, I need to set the name of the curve in a dynamic way in order to assign different curves to the DiscFactorsCurveName variable and maintain constant the script.

CurveName is the curve object (discount type)

Dates is the vector of input dates

DiscFactorsCurveName=toRateSpec(CurveName,Dates);

I need to assign a different curve object to the CurveName, for example Curve1, Curve2, Curve3, etc...

Have you any suggestions please?

Thank you very much in advance.

Angelo

[Stephen23]

"I need to assign a different curve object to the CurveName, for example Curve1, Curve2, Curve3, etc..."

I very much doubt that you need to do that. What is much more likely is that you want to do that:

https://xyproblem.info/

"Have you any suggestions please?"

Do not access variable names dynamically... unless you really want to force yourself into writing slow, complex, inefficient, obfuscated, fragile code that is hard to debug.

A much better approach would be to use an array (e.g. a cell array or structure array) and basic MATLAB indexing.

So far you have not told us the most important information: how did you get all of those differently-named variables into the MATLAB workspace? Hopefully not by sitting there and writing all of their unique names one-by-one.

[Angelo Amoroso]

Thanks Stephen, I'm aware that dynamic variable are discouraged in matlab scripts, nevertheless I posted the question to avoid writing names one-by-one. If an indexing solution may solve the problem in more efficiently way I would appreciate. I answer to your last question: I mean to take input from an excel file in which I could associate for every deal instrument a curve for discounting and, in case, also another one for accruing. Every record in the matrix could have one or two curve among a set of curves.

[Stephen23]

"...I mean to take input from an excel file in which I could associate for every deal instrument a curve for discounting..."

Then you can simply import your data into one table/matrix/structure/whatever and use indexing.

So far nothing seems to prevent you from doing that. But as long as you keep your explanation very high-level then the advice you will get will also remain very high-level. If you want more concrete advice then please show some actual code you are using, preferably with some actual data files.

[Steven Lord]

maintain constant the script.

If you're writing this code as a script file, I'd consider converting it into a function file. That way, whatever name you use inside the function will be completely independent of what name(s) you use outside.

% part 1 of example
x1 = [1 2 3 4];
p = myprod(x1)

p = 24

x2 = 5:8;
p = myprod(x2)

p = 1680

x3 = [9 10; 11 12];
p = myprod(x3)

p = 11880

% Part 2 of example
X = randperm(12)

X = 1×12

12 4 11 9 1 6 3 7 10 2 5 8

for k = 1:4:12
    fprintf("Taking the product of X(%d:%d) = %s\n", k, k+3, mat2str(X(k:k+3)))
    p = myprod(X(k:k+3))
end

Taking the product of X(1:4) = [12 4 11 9]

p = 4752

Taking the product of X(5:8) = [1 6 3 7]

p = 126

Taking the product of X(9:12) = [10 2 5 8]

p = 800

function theOutput = myprod(theInput)
theOutput = prod(theInput(:));
end

Note that I did use numbered variable names x1, x2, and x3 in the first part of the example. I did that for illustration purposes only. When I wanted to "automate" this, in the second, I created "unnamed" temporary variables using indexing to pass into myprod. Note that nowhere outside myprod did I create any variables named theInput or theOutput, but MATLAB was able to handle passing the data into and out from the function just fine.

[Angelo Amoroso]

Hi Stephen and Steven,

I'm sorry not to have reply you earlier, thank you for your suggestion. I'm aware my question was a bit high-level as you noticed. I'm not so expert to solve this kind of issues, even if them may appear simple to you.

I wrote a script to create curve object for each curve I may use, then a schedule of dates for a financial instrument. The forward step is to associate to the dates discount factors and forward rates from the curve objects created.

How can I handle an indexation or/and a "cycle for" solution to chose one of the n curves for every operation to calculate? I imagine to start from an excel input file like the one attached.

Is it possible to calculate as a matrix composed of several operation for which to calculate cash flows profiles of different lenghts or I have to use a cycle for to calculate one by one?

Please let me know if I didn't manage to be clear and many thanks to you all for your support.

Kind regards

Angelo

Answer 1

[Shivam]

Hello Angelo,

Based on your shared information, it seems you are interested in dynamically allocating various IRDataCurve objects and their corresponding RateSpec objects to distinct variables.

A systematic way to handle this would be to use MATLAB's structures to store and retrieve these objects. This method lets you dynamically assign names and efficiently organize multiple curves with their respective RateSpec objects.

You can have a look at the example code that demonstrates how IRDataCurve and RateSpec objects are stored in structures under dynamically generated names:

curve = struct();
rateSpec = struct();

for i = 1:2
    curveName = sprintf('Curve%d', i); % Curve will be created as Curve1, Curve2, Curve2, etc.
    % Creating dummy data
    CurveSettle = datetime(2016,3,2);
    Data = [2.09 2.47 2.71 3.12 3.43 3.85 4.57 4.58]/100;
    Dates = datemnth(CurveSettle,12*[1 2 3 5 7 10 20 30]);
    
    % Create IRDataCurve object dynamically
    curve.(curveName) = IRDataCurve('Zero',CurveSettle,Dates,Data,'Compounding',4,'Basis',4);
    
    % Create rateSpec object dynamically
    rateSpecName = sprintf('RateSpec%d', i);
    rateSpec.(rateSpecName) = toRateSpec(curve.(curveName), Dates);
end

Also, you can access a specific object as follows:

selectedCurve = curve.Curve2;
selectedRateSpec = rateSpec.RateSpec2;

You can refer to the documentation provided to know more about 'IRDataCurve' and 'toRateSpec':

• https://www.mathworks.com/help/releases/R2024a/fininst/irdatacurve.html
• https://www.mathworks.com/help/releases/R2024a/fininst/toratespecirdatacurve.html

I hope it helps.

[Stephen23]

Note: using actual indices would likely be simpler and more efficient than forcing pseudo-indices into fieldnames.

[Angelo Amoroso]

Hi Shivam,

thank you for your suggestion, it seems to me very intersting. Do you think this solution may apply in case I mean to take the input from an excel file where for every deal I indicate a curve name to use?I'll try to apply and then let you know.

Thank you very much

[Shivam]

Hi Stephen,

In the case where you provide a specific curve name rather than using the generic Curve1, Curve2, and so forth, the described approach remains effective. Rather than dynamically generating the name, you have the option to store the curve objects under the names you provide. If this doesn't solve the problem, please do let me know.