# 2. Systematic code examples: a guided tour of Numscrypt

One ready-to-run code example is worth more than ten lengthy descriptions. The autotest and demo suite, that is part of the distribution, is a collection of sourcecode fragments called testlets. These testlets are used for automated regression testing of Numscrypt against CPython. Since they systematically cover all the library constructs, they are also very effective as a learning tool. The testlets are arranged alphabetically by subject.

Autotest: Numcrypt autotest demo suite

    import org.transcrypt.autotester

    import basics

    autoTester = org.transcrypt.autotester.AutoTester ()

    autoTester.run (basics, 'basics')

    autoTester.done ()

## 2.1. Basics: creating and using arrays

Testlet: basics

    from org.transcrypt.stubs.browser import *
    from org.transcrypt.stubs.browser import __main__, __envir__, __pragma__

    if __envir__.executor_name == __envir__.transpiler_name:
        import numscrypt as num

    __pragma__ ('skip')
    import numpy as num     # Bundling: import has to be known compile time
    __pragma__ ('noskip')

    def run (autoTester):
        z = num.zeros ((4, 3, 2), 'int32')
        autoTester.check ('Zeros', z.tolist (), '<br>')

        o = num.ones ((1, 2, 3))
        autoTester.check ('Ones', o.astype ('int32') .tolist ())

        i = num.identity (3, 'int32')
        autoTester.check ('Identity', i.tolist (), '<br>')

        # shape: 2 blocks x 3 rows x 4 columns
        a = num.array ([
            [
                [1, 1, 2, 3],
                [4, 5, 6, 7],
                [8, 9, 10, 12]
            ], [
                [100, 101, 102, 103],
                [104, 105, 106, 107],
                [108, 109, 110, 112]
            ]
        ])

        autoTester.check ('Matrix a', a.tolist (), '<br>')

        b = num.array ([
            [
                [2, 2, 4, 6],
                [8, 10, 12, 14],
                [16, 18, 20, 24]
            ], [
                [200, 202, 204, 206],
                [208, 210, 212, 214],
                [216, 218, 220, 224]
            ]
        ])

        autoTester.check ('Matrix b', b.tolist (), '<br>')

        c = num.array ([
            [1, 2, 3, 4],
            [5, 6, 7, 8],
            [9, 10, 11, 12],
        ])

        d = num.array ([
            [13, 14],
            [15, 16],
            [17, 18],
            [19, 20]
        ])

        __pragma__ ('opov')
        sum = a + b
        dif = a - b
        prod = a * b
        quot = a / b
        dot = c @ d
        __pragma__ ('noopov')

        autoTester.check ('Matrix sum', sum.tolist (), '<br>')
        autoTester.check ('Matrix difference', dif.tolist (), '<br>')
        autoTester.check ('Matrix product', prod.tolist (), '<br>')
        autoTester.check ('Matrix quotient', quot.tolist (), '<br>')
        autoTester.check ('Matrix dotproduct', dot.tolist (), '<br>')