Random Numbers Below 1

[Timothy Smith]

Hi Community,

I’m looking to generate random numbers between 0.4 and 0.5. What’s best way to use the MathRand() function to do this?

Cheers, Tim

[William Roeder]

If you had used this, you would have found this: MathRand between 3000 and 5000 - Forex Trading Tutorial - Expert Advisors and Automated Trading - MQL5 programming forum (two weeks ago) and RandomLinear (2019)

RandomLinear(30000)/300000.0+0.4; // [0.40000 … 0.4999966666666667] increments of 0.000003333
RandomLinear(10000)/100000.0+0.4; // [0.40000 … 0.49999] increments of 0.00001
RandomLinear(5000,4000)/10000;    // [0.40000 … 0.49999] increments of 0.0001

[Antonio Simon Del Vecchio]

Timothy Smith:

Hi Community,

I’m looking to generate random numbers between 0.4 and 0.5. What’s best way to use the MathRand() function to do this?

Cheers, Tim

MathRand()  returns a pseudorandom integer within the range of 0 to 32767.

Number between 0.4 and 0.5 is: 

double Number = 0.4 + MathRand() * (0.5 - 0.4) / 32767.;

[Timothy Smith]

Antonio Simon Del Vecchio #:

MathRand()  returns a pseudorandom integer within the range of 0 to 32767.

Number between 0.4 and 0.5 is: 

Thanks for your help Antonio, this community is awesome.

[Timothy Smith]

William Roeder #:

If you had used this, you would have found this: MathRand between 3000 and 5000 - Forex Trading Tutorial - Expert Advisors and Automated Trading - MQL5 programming forum (two weeks ago) and RandomLinear (2019)

Thanks for your help with this William, much appeciated!

[William Roeder]

Antonio Simon Del Vecchio #: Number between 0.4 and 0.5 is: 

double Number = 0.4 + MathRand() * (0.5 - 0.4) / 32767.;

1. Read the links I provided. Your code does not generate numbers of equal frequency. There is only a 1/32768 (.00003) chance of 0.5. There is a 3/32767 (.000091) chance of 0.4
   
2. It also generates values between [0.4 and 0.5] inclusive. Inclusive was not specified, like a clock 0000…2400 does not include 2400.