big x^y modulo function

provide the solution when the normal mod function can't because the input is to big

Description

In some fields as cryptology (RAS-cryption), there is a need of doing x^y mod m where x, y and n are huge. The build-in maltab function can't achieve the result because it first calculate x^y and found it is equals to inf. The hereunder function provides a performent solution to this problem and gives the right answer...

• Acknowledgements: This submission has inspired the following:; big modulo function
• MATLAB release: MATLAB 6.0 (R12)

[Muhammet UNAL]

thank you! exactly what I need

[bennyboss n/a]

many thanks! I must say the same, exactly what I need.

[Pavel Stepanek]

thank you, that is the what I need. I am very surprised, that standard mod function in Matlab does not work well for me, even if input is relatively small, e.g. mod(8^51,103) produce
 1.267650600228229e+030 instead of 58. Has anybody idea, why it is so?

[Pavel Stepanek]

Sorry, mod(8^51,103) should produce 1.